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

The description discloses significant behavioral traits beyond the schema: the tool costs 0.001 USD per call, payments are final and non-refundable, and it returns HTTP 402 until payment is presented. It also clarifies that the provider never receives funds and relays a quote. This is valuable context for an agent deciding whether to invoke the tool.

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 description is somewhat bloated with payment terms and untrusted-provider content, but the core functional sentence is clear and front-loaded. The payment details are necessary for behavioral transparency but could be more concise. The untrusted-provider wrapper adds noise.

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?

For a validation tool with 3 parameters and no output schema, the description covers the core function, supported drafts, and critical payment behavior. It doesn't describe the return format, but the description says it returns every error with its instance path, which is sufficient for an agent to understand the outcome.

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 67%: 'data' and 'schema' have descriptions, but 'draft' only has an enum and default. The description adds the supported draft versions (2020-12, 2019-09, draft-07), which maps to the 'draft' parameter, but it doesn't add much beyond the schema. Baseline 3 is appropriate.

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?

The description states a specific verb and resource: 'Validates a JSON document against a JSON Schema' and lists supported drafts. It clearly distinguishes the tool's function from siblings like regex-test or csv-to-json, though it doesn't explicitly name a sibling alternative.

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?

The description implies usage context: use this tool when you need to validate a JSON document against a JSON Schema and get every error with its instance path. It does not explicitly state when not to use it or name alternatives, but the context is reasonably clear.

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