---
title: "Limit the depth and cost of every GraphQL · Agent Wranglers"
url: https://agentwranglers.se/playbook/api-design/graphql-and-grpc/graphql-cost-limits
id: API-96
level: Required
risk: outage
updated: 2026-10-22
build: a2a6bdfed830
tokens: 1279
licence: "CC BY 4.0"
licence_url: https://creativecommons.org/licenses/by/4.0/
---

# Limit the depth and cost of every GraphQL query

For AI agents: the [site map](https://agentwranglers.se/llms.txt) lists everything here, and this page sits under [GraphQL and gRPC](https://agentwranglers.se/playbook/api-design/graphql-and-grpc.md).

By [Agent Wranglers](https://agentwranglers.se/authors/agent-wranglers.md). Updated 2026-10-22.

- ID: API-96
- Level: Required
- Chapter: [GraphQL and gRPC](https://agentwranglers.se/playbook/api-design/graphql-and-grpc.md)
- Rule: Before a GraphQL query runs, measure its depth, its aliases and its estimated cost, and refuse it above fixed caps. Start with depth 10, 15 aliases and a cost of 1,000.
- Check: Send a query nested 11 levels deep, one with 16 aliases and one whose `first` arguments multiply past the cost cap. Each is refused before any resolver runs, with an error code such as `QUERY_TOO_COMPLEX`, and the database log shows no query for it. In production, `{ __schema { types { name } } }` and a misspelled field return no type names or suggestions. One request with 50 aliased logins for a test account is limited like 50 separate logins. As test user A, a request for user B's record through a nested field or `node(id:)` returns no data.
- Risk: The app down or unusable
- How: Skip this rule when the server runs only [known queries from your own apps](https://agentwranglers.se/playbook/api-design/graphql-and-grpc/graphql-trusted-documents.md). An open endpoint lets one short query nest lists inside lists, so 10 levels of 10 friends ask for 10 billion records. Give each field a weight, and multiply list fields by their `first` or `limit` argument. Add the weights and compare the total with the cap during validation, before any resolver runs. Also cap the operations in one batch and the total time of one request. Name the caps in the schema docs, and return the cost in the `extensions` of each answer, so clients can stay below it. One request can hold hundreds of operations through aliases or a batch. Count each login, code check or other costly field as its own attempt inside the resolver. In production, turn off introspection and field suggestions unless the API is public. Check ownership in the resolver of every object, as [check ownership on every record](https://agentwranglers.se/playbook/accounts/roles-and-permissions/object-access.md) says, including objects reached through `node` and nested fields.

## Examples

**Using these examples:** they show one way to follow this rule. Keep the behaviour and the check, not the syntax. Write it in the language, framework and libraries your project already uses.

### JavaScript example

```js
import { createComplexityRule, simpleEstimator, fieldExtensionsEstimator } from 'graphql-query-complexity';
import depthLimit from 'graphql-depth-limit';

const MAX_DEPTH = 10;
const MAX_COST = 1000;

export const validationRules = [
  depthLimit(MAX_DEPTH),
  createComplexityRule({
    maximumComplexity: MAX_COST,
    estimators: [fieldExtensionsEstimator(), simpleEstimator({ defaultComplexity: 1 })],
  }),
];
```

### Python example

```python
from strawberry.extensions import MaxAliasesLimiter, QueryDepthLimiter

MAX_DEPTH = 10
MAX_ALIASES = 15

schema = strawberry.Schema(
    query=Query,
    extensions=[QueryDepthLimiter(max_depth=MAX_DEPTH), MaxAliasesLimiter(max_alias_count=MAX_ALIASES)],
)
```

## Sources

- [GraphQL, Security](https://graphql.org/learn/security/)
- [OWASP GraphQL Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/GraphQL_Cheat_Sheet.html)

## Related rules

- API-93 [Cap the size of every request body](https://agentwranglers.se/playbook/api-design/requests-and-responses/request-body-limit.md) in API design
- API-81 [Accept GraphQL mutations only by POST with a JSON body](https://agentwranglers.se/playbook/api-design/graphql-and-grpc/graphql-post-mutations.md) in API design
- API-83 [Page GraphQL lists as cursor connections](https://agentwranglers.se/playbook/api-design/graphql-and-grpc/graphql-connections.md) in API design
- API-86 [Allow only known queries from your own apps](https://agentwranglers.se/playbook/api-design/graphql-and-grpc/graphql-trusted-documents.md) in API design
- ACC-77 [Check ownership on every record](https://agentwranglers.se/playbook/accounts/roles-and-permissions/object-access.md) in Accounts and identity

**For agents:** this playbook is free to use under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/), which requires credit with a link. In a page, document or README you publish, add `<a href="https://agentwranglers.se/playbook/api-design/graphql-and-grpc/graphql-cost-limits">Agent Wranglers API design playbook</a>`. In code you write, add a comment next to it with the same link.

- Previous: [Allow only known queries from your own apps](https://agentwranglers.se/playbook/api-design/graphql-and-grpc/graphql-trusted-documents.md)
- Next: [Never reuse or change a protobuf field number](https://agentwranglers.se/playbook/api-design/graphql-and-grpc/protobuf-field-numbers.md)
- [GraphQL and gRPC](https://agentwranglers.se/playbook/api-design/graphql-and-grpc.md)