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

With no annotations, the description carries the full burden. It usefully discloses data-availability semantics (obsMappingState, runtimeObservation 'when available', do not treat absent observations as zero, production latency is not a test threshold), but says nothing about permissions, rate limits, or behavior when the operation cannot be resolved.

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?

Front-loaded with purpose, then interpretation caveats, then parameter-selection order; each sentence carries information. The em-dash run-on makes it dense to parse, but nothing is padding.

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 an 8-parameter, zero-annotation, no-output-schema tool, the description covers return content and selector logic well, but leaves three parameters (serviceKey, includeManual, includeRemoved) undocumented and does not explain resolution/failure behavior, so an agent still has gaps before calling it.

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 0% across 8 parameters, so the description must compensate. It documents the three selector patterns covering id, rootFilePath, oasOperationId, httpMethod and pathTemplate, but leaves serviceKey, includeManual and includeRemoved completely undefined in both schema and description.

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 (Fetch) and resource (detailed API operation coverage) and enumerates the payload (request/query/response fields, response codes, covering tests). It is clearly a single-operation detail tool, distinguishable by name from list-api-operations, but it never names or contrasts 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?

Provides concrete usage guidance: rank coverage risk by request volume/error rate, prioritize perf work by p95/p99 latency, and prefer the id selector over rootFilePath combinations. It does not, however, say when to call this versus list-api-operations or list-api-operation-interactions.

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