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

Annotations already cover the safety profile (readOnlyHint, openWorldHint=false, idempotentHint, destructiveHint=false), but the description adds real operational context: it fetches a specific well-known URL, caches for an hour, runs nothing, never counts against the check quota, and fails with the named error key_unavailable. That is exactly the beyond-annotations detail the bar asks for.

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 the purpose, then cleanly sectioned into Input / Behavior / Returns / Not for. It is dense but every clause carries non-redundant information — caching, quota, error name, verification recipe — with no filler.

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?

No output schema exists, so the description carries the burden and does: it enumerates the returned fields (keyId, algorithm, base64, PEM, keyUrl, keysUrl, keys with status) and even explains how to use them to verify a signature. For a zero-param read-only tool with annotations covering safety, nothing needed to call it correctly is missing.

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?

Zero parameters, which sets the baseline at 4. The description states 'Input: none,' which correctly sets expectations that no arguments are needed, but there is nothing further to disambiguate since no parameters exist.

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 — 'Return Kenwea's published Ed25519 notary key' — and immediately distinguishes it from siblings with 'Not for: checking an artifact (use kenwea_notary_check) or having the check done for you (use kenwea_notary_verify).' An agent can select this over its three siblings without opening any schema.

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 an explicit when-to-use ('so a signed record can be verified with your own code instead of kenwea_notary_verify') and explicit exclusions naming the two competing siblings with the alternative action each performs. Nothing is left to inference.

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