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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered; the description adds genuinely useful behavior: the live source URL, the partial-match nature of the endpoint filter, and the non-obvious rule that 'all' excludes large component schemas. It does not mention latency, caching, or response size limits for a live network fetch, which keeps it from a 5.

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 intent is front-loaded in the first two sentences, but the closing sentence ('Also use this to look up: what errors can a specific endpoint return, what are the exact parameter constraints, what does a 400/403/422/429 response look like') restates content already given and pads the definition with no new information.

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?

With no output schema, the description carries the return-value burden and does so: it promises structured field definitions, required flags, and error codes. The only missing element is any hint about response volume or pagination when no endpoint filter is supplied, which matters for a spec of this size.

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 coverage is 100% and two params have enums, so the schema already documents query, method, section and endpoint thoroughly. The description only echoes the endpoint examples and the 'all excludes schemas' caveat that the schema itself states, adding little new semantics — baseline 3 applies.

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 ('fetches the live Yield.xyz OpenAPI spec') and enumerates what can be retrieved: body schemas, constraints, error shapes, operationIds. It is clear what the tool does, but it never distinguishes itself from similar siblings like yield_fetch_doc or yield_lookup_docs, which an agent could easily confuse with this one.

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?

Gives concrete triggers ('Use when you need exact request body schemas, field constraints, error response shapes') and an explicit directive ('Use this instead of guessing field names — the spec is the ground truth'). It lacks any exclusion or routing statement relative to the doc-fetching siblings, so it stops short of a 5.

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