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

No annotations are provided, so the description bears full responsibility. It fully discloses that the tool is a parser that does not fetch, lists all markers it extracts, and describes what it returns (per-source ISO dates, freshest source, cross-source spread, heuristic flags). This leaves no ambiguity about its behavior.

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 a single paragraph but packs significant information efficiently. It front-loads 'Pure parser (no fetching)' as the key caveat. Every sentence adds value; however, it could be broken into smaller sections for readability.

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?

Given the tool's complexity (four parameters including nested objects, no output schema), the description is remarkably complete. It explains the purpose of each parameter, enumerates all extracted markers, and describes the return value components (per-source dates, freshest source, spread, heuristic flags). It also ties the tool to a specific usage context (geo-aeo-readiness skill).

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% with descriptions for all four parameters. The tool description adds context beyond the schema: url is 'for context', headers are expected with 'lowercased keys', and sitemapEntry is a 'parsed sitemap entry'. It does not fully detail the structure of the output object but compensates by listing return fields in free text.

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 it is a 'pure parser (no fetching)' and enumerates exactly which freshness markers it extracts (HTTP Last-Modified, sitemap lastmod, JSON-LD dates, etc.). It identifies the tool's resource (freshness markers in HTML) and distinguishes it from sibling tools like 'get_page' (which fetches) by emphasizing it does not fetch.

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 specifies the tool is for extracting freshness signals and notes its use in the 'geo-aeo-readiness skill's freshness check'. It implies when to use (when you need to parse freshness markers from already-fetched HTML) but does not explicitly state when not to use it or provide direct comparisons to alternatives among the siblings.

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