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

Annotations already establish readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds genuinely useful context beyond that: 'Runs nothing and fetches only the public key' and the non-obvious semantics that an altered record returns valid=false with a reason rather than throwing an error.

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?

Dense but front-loaded, leading with what the tool does before the invocation caveat and the return shape. Slightly long, but every sentence carries operational value; nothing reads as 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?

With no output schema, the description enumerates the returned fields (valid, keyId, and signed facts including artifactRef, contentSha256, verdict, ran, exitCode, issuedAt) and states the failure mode. Combined with annotations covering safety, an agent has everything needed to call and interpret it correctly.

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%, so baseline is 3, but the description adds real meaning beyond the schema: payload is a JSON string that 'must not be re-serialised, or the signature will not match' — a byte-exactness constraint the schema does not convey. contentSha256's purpose (confirming the record is about the bytes you hold) is also clarified.

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 ('Check a signed record') and names the sibling that produces the input (kenwea.notary.check), making the check/verify split unambiguous. It also enumerates what is being determined: signature validity under the Ed25519 key and what the record attests.

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?

Specifies the input provenance ('pass payload and signature exactly as they appear in the record's signedAttestation'), the optional confirmation use case for contentSha256, and even the alternative no-server path via any Ed25519 library. An agent knows when and how to reach for this versus the sibling.

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