Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false). The description adds some billing/auth context ('FREE during validation', 'No key, credits, wallet or preparation needed') and a rate limit note ('Existing source and input limits apply'), which is genuinely useful beyond annotations, but the phrasing is boilerplate and vague.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The core purpose is front-loaded effectively, but the middle billing sentence ('FREE... No key, credits, wallet or preparation needed') is repetitive and the closing 'Supply your task in input' is awkward filler. Roughly half the sentences do little work.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists so return values need not be explained, but this tool's sole input is a nested document object with 0% schema coverage, and the description gives no detail about what the document must contain. For a validator whose correctness depends on input shape, this is incomplete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0% and there is one required nested parameter (input.document). The description only says 'Supply your task in input,' which tells the agent nothing about the required document object or its structure, so it fails to compensate for the coverage gap.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource: 'Validate OpenAPI 3.0 JSON structure and internal references.' This distinguishes it from the sibling contracts_jsonschema_validate (JSON Schema, not OpenAPI) and contracts_openapi_diff, though it never names those siblings explicitly.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

There is no when-to-use guidance, no conditions for choosing this over contracts_jsonschema_validate or contracts_openapi_diff, and no prerequisites. 'Supply your task in input' is procedural filler rather than routing guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.