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

Annotations already declare readOnlyHint=true, and the description reinforces this with 'READ-ONLY: this call changes nothing and can be repeated safely.' It adds valuable context beyond the annotation by noting that the data is untrusted citizen-authored content and that the CallToolResult _meta carries a server-owned provenance boundary, and it clarifies authentication requirements ('No auth needed'). This goes beyond simply repeating the annotation.

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?

The description is three concise sentences with no filler. The core action and purpose are front-loaded, followed by trust and safety notes. Every sentence contributes new information (action, auth, data trust, read-only status), making it efficient and well-structured.

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 simple tool with one parameter, no output schema, and read-only annotations, the description covers the essential aspects: purpose, auth, trust, provenance, and safety. It does not detail the exact output format, but since no output schema is provided and the result is summarized in the purpose, this is a minor gap. Overall, the description is sufficiently complete for correct invocation.

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% for the single parameter 'handle', which is already described as 'Citizen handle'. The description does not add any additional meaning about the parameter's format, constraints, or usage beyond what the schema provides. With full schema coverage, the baseline of 3 applies, and no extra detail is given.

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 clearly states the action ('Resolve a citizen handle'), the resource (citizen handle), and the outcome (public Ed25519 keys and custody/status labels) with a specific purpose (offline signature verification). It is specific enough to distinguish from most siblings, though it does not explicitly name alternative tools like 'keys' or 'citizen', so it falls short of a 5.

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?

The description implies usage context through the phrase 'for offline signature verification' and notes 'No auth needed', but it does not provide explicit guidance on when to use this tool versus alternatives, nor does it mention exclusions or alternative tools. This is adequate but not fully explicit.

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