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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, so safety and repeatability are covered. The description adds genuinely new context beyond that: the signing algorithm, the contents of the response, and how the envelope is verified against the JWKS endpoint with kid rnwy-mcp-v1. Missing are any auth requirements, rate limits, or failure modes, 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?

Two sentences, no filler, and the core purpose leads. The verification details are packed densely into the second sentence, which is efficient though somewhat jargon-heavy for a reader unfamiliar with JWKS or kid values.

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 single-parameter, read-only tool with no output schema, the description covers what it produces (risk score, threat findings, signed envelope) and how the result can be verified, which is the information an agent most needs. It stops short of stating error behavior or whether results are cached per canonical_id.

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?

Only one parameter exists and schema description coverage is 100%, so canonical_id is already documented with an example in the schema. The description adds no format or resolution guidance beyond it, which is the expected baseline when the schema does the lifting.

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 names a specific artifact and verb: an ES256-signed attestation for an MCP server, and enumerates its payload (risk score, threat findings, signed envelope). That is far more concrete than a tautology, but it never contrasts itself with adjacent tools such as trust_check or risk_terms, so an agent must infer which one to reach for.

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 statement, no exclusion, and no named alternative. The phrase 'for any MCP server' scopes the input domain, but it does not tell the agent under what circumstances this attestation should be requested instead of a sibling's assessment.

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