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

Annotations already mark readOnlyHint=true, and the description adds valuable context beyond that: it reveals the credential-free access ('Needs no credential') and explains the semantic of the `retry` field with three enumerated values (`later`, `fix_request`, `needs_human`) and what each implies. This is behavioral disclosure that helps an agent interpret the output without guessing.

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 four sentences, front-loaded with the core purpose, then the credential note, then the retry-field explanation, and a closing recommendation. Every sentence adds value; there is no fluff or redundancy.

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 read-only, parameterless tool with an output schema, the description covers the essential context: what it returns (all refusals), how to use it (without credentials, even after a refusal), and how to interpret the key field. The output schema presumably details the structure, so the description doesn't need to list every refusal. It is complete for an agent to decide when to call and how to act on the response.

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?

There are zero parameters and the schema is an empty object, so the description has no parameters to document. The baseline for 0 params is 4, and the description correctly focuses on output semantics instead. No gaps exist in parameter documentation.

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 opens with a precise statement: 'Every refusal this server can return, and what to do about each.' This identifies a specific resource (the catalog of refusals) and its purpose (guidance on handling each), distinguishing it from sibling action-oriented tools. The verb 'read' is implicit but clear, and the scope is unambiguous.

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 explicitly states when to use it: 'Needs no credential — you can read it before you have one, or after a refusal has told you the one you had is gone.' It also advises 'Read it once and stop guessing whether a 409 is worth retrying,' which guides agents to consult it for retry decisions. It doesn't name alternatives, but as a unique reference tool the context is sufficient.

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