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

Annotations already cover readOnly, idempotent, non-destructive and closed-world behavior, so the bar is lower. The description still adds real context: a url field is not fetched (relevant for an agent worried about SSRF side effects), nothing is stored, and the conditional null vs. page behavior of answer_page. The 'Nothing is for sale' line is filler rather than disclosure.

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 key facts (return shape, conditional answer_page) are front-loaded and the fragment style is compact. However, 'Nothing is stored. Nothing is for sale.' is an unexplained aside that does not earn its place, and the sentences are choppy enough to read as accumulated boilerplate.

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?

An output schema exists, so return values need not be re-explained, yet the description usefully clarifies the one non-obvious output case (answer_page is populated only for GLC-CSP-MISSING and GLC-FRAME-MISSING). For a single-enum-parameter lookup tool this is essentially complete; only the sibling routing 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?

There is a single parameter with 100% schema description coverage and an explicit enum, so the schema carries the semantics. The description only restates the id set and notes unknown fields are ignored, which the schema also states. 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 (one finding id from a fixed set of seven) and enumerates the return shape (id, severity, why, answer_page). This is clearly distinguishable from get_fix in intent, though the description never names or contrasts the sibling tools explicitly.

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?

Usage is implied: 'one finding id from the seven' tells the agent this operates on ids surfaced by analyze_headers, and the enum constrains it to that set. But there is no explicit when-to-use versus get_fix or report_feedback, and no statement of prerequisites or when not to call it.

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