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

Annotations already establish a safe read-only, closed-world operation, and the description adds meaningful extra context: results come from saved fixtures, per-vendor last_run dates are source observations with unknown generation time, and the audit may be unavailable or stale. That staleness/limitation disclosure is exactly the behavioral value structured fields don't carry.

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?

Compact at roughly four sentences, and the core comparison subject is front-loaded. It is dense with caveats but each clause (fixtures, staleness, no live tests, no cost comparison) carries distinct information, with minimal waste.

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 no output schema, the description does the work of describing returns (text/code/table scores plus latency) and flags data-freshness limits. For a zero-parameter read-only comparison tool this is close to complete, though it could state the vendor coverage scope more explicitly.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; the baseline for a no-arg tool is 4. No schema semantics are being missed.

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 names the specific comparison subject (Firecrawl, Jina Reader, DIY extraction) and the basis (saved documentation fixtures / saved RAG benchmark), so an agent can tell it apart from siblings like compare_scrapers and compare_scraping_apis. It opens as a rhetorical question rather than a declarative verb+resource, which slightly blunts clarity.

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?

It implies the usage context ('saved RAG benchmark', 'No live tests or comparable cost'), telling the agent this is a fixture-based rather than live comparison. However, it never explicitly states when to pick this over the sibling comparison tools (compare_scrapers, compare_scraping_apis, compare_proxy_providers), leaving routing to inference.

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