When the model call is the product, spend is cost of goods sold

In a traditional SaaS business an extra user costs almost nothing to serve. In an AI-native one, every session has a variable cost that lands on a provider invoice a month later. That changes the unit economics from a rounding error into the thing the business is made of, and it means a pricing decision made without per-customer cost is a guess.

Try for free Read the docs

What a provider dashboard leaves you with

01
One API key serves every customer, so the provider dashboard can only ever show one total for all of them.
02
A heavy customer on a flat plan is indistinguishable from a light one until margin is calculated by hand, quarterly.
03
A prompt change that doubles token use ships on a Tuesday and is discovered on the invoice.

What Capsera does about it

Gross margin per customer: Spend attributed to the end customer, not just the account, so the plan a customer is on can be checked against what serving them actually costs.
A budget per agent, enforced: The limit is checked in-process before the provider call, so an expensive customer or a looping agent is refused rather than reconciled after billing.
Cost-aware routing: Route to a cheaper model where a cheaper model would do, per agent, without changing the call sites.

The number this is judged on

Gross margin per customer

None of this is assumed. We scanned 133 public agent repositories and found a cost defect in most of the ones making live model calls.

Read the method and limitations

import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")

    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()

assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)

 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",

 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):

)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:

        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic

def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)

for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02

from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(

)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:

 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)

import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")

    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()

assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)

 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",

 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):

)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:

        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic

def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)

for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02

from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(

)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:

 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)

import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")

    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()

assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)

 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",

 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):

)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:

        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic

def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)

for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02

from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)
 
# checked before the call
capsera.budget(
    monthly=500,
    on_exceed="block",
)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(

)
 
with capsera.agent("summarizer"):
    client = Anthropic()
    resp = client.messages.create(
        model="claude-sonnet-4-6",
        max_tokens=1024,
    )
 
# no proxy, no gateway
assert resp.usage.cost < 0.02
 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:

 
if capsera.over_budget():
    raise BudgetExceeded()
 
@capsera.track()
def extract(doc):
    return chain(doc)
 
# cheaper route, same output
capsera.route(prefer="cost")
 
spend = capsera.usage(
    group_by="agent",
    window="30d",
)
 
for a, cost in spend:
    print(a, f"${cost:.2f}")
 
# fails open, always
capsera.flush()
 
for task in queue:
    run(task)
 
log("run complete")
import capsera
from anthropic import Anthropic
 
capsera.init(
    agent="reasoning_agent",
    run_id=ctx.run_id,
)

Know what each customer costs you to serve.

Stop runaway agents before they become runaway invoices.

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