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

Adds genuine behavioral context beyond the annotations: outputs are 'bounded free checks' (cost/scope guarantee) and it 'never performs a repair or payment'. This usefully narrows what the agent can expect even though annotations carry destructiveHint=false and openWorldHint=true. There is mild tension with readOnlyHint=false (the description reads like a non-mutating inspection tool), but not a direct contradiction.

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?

Two tight sentences with zero filler; the diagnostic scope is front-loaded and the non-mutation guarantee follows immediately. Every clause earns its place.

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-value explanation is unnecessary, and the description adequately covers the tool's domain and safety envelope. But for a 5-parameter tool with 0% schema coverage, it supplies no parameter-level guidance and no explicit routing to the sibling diagnosers, leaving real gaps.

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% across 5 parameters (error_message, context, transport enum, error_code, protocol_version), and the description contributes nothing about any of them — no guidance on the required error_message, the meaning of 'context', or the transport enum. The description entirely 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 ('Diagnose') and a well-scoped resource: MCP initialize, discovery, transport, capability and tool-schema failures. This is clearly distinct in domain from the sibling diagnosers (auth 401, JSON schema, webhook signature), but the description never names or contrasts those siblings, so an agent must infer the boundary itself.

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?

'Returns bounded free checks and never performs a repair or payment' establishes an important exclusion (no repair, no cost) and implies this is a safe diagnostic entry point. However, there is no explicit 'use this when X, use diagnose_api_auth_401 when Y' routing, and no statement of prerequisites such as needing a captured error message.

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