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

Annotations already cover safety (readOnly, idempotent, non-destructive), so the 'Read only' sentence adds nothing. The description does contribute real context beyond the annotations: the coverage boundary of 64 common codes, including named Cloudflare 520/522/524, which tells the agent this is a bounded lookup rather than a general HTTP reference. It stops short of saying what happens for codes outside that set.

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, front-loaded with the triggering situation before the return contract. Every clause carries information; the trailing 'Read only' is the only redundant fragment and it costs nothing.

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 an output schema present, the description needn't detail return values, and it still summarizes them accurately. Coverage is bounded to 64 codes without stating behavior for unlisted codes, which is the only real gap for a one-parameter lookup tool.

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% and the single parameter is fully documented with range and examples (429, 503), so the schema carries the load. The description adds no format or edge-case guidance for the code input beyond the Cloudflare examples, so baseline 3 applies.

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 (explain) and resource (HTTP status code) and spells out the three things it returns: meaning, corrective action, and retry decision. The agent can tell exactly what class of question this tool answers.

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?

Opens with an explicit trigger condition — 'when a request failed with an HTTP status code and you need to know what it means, what to change, and whether retrying is safe.' No exclusions or alternatives are named, but the sibling tools are unrelated, so there is no realistic confusion to resolve.

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