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

Annotations already declare readOnly, openWorld, idempotent, non-destructive, so safety is covered. The description adds real context beyond them: the discrete check types, the four-valued outcome vocabulary (pass/warn/fail/unavailable), that the response includes the curl to reproduce each check, and a rate limit of 5 per hour. It does not say whether results are cached or how long a check takes.

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?

Four tight clauses: what it checks, what the result looks like, where the fuller alternative lives, and the rate limit. The most decision-relevant facts (free, quick, sample vs full report) are front-loaded with no filler.

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 only one parameter, no output schema, and annotations covering the safety profile, the description supplies everything else an agent needs: the checks run, the outcome vocabulary, reproducibility via curl, the rate limit, and the pointer to the heavier sibling. Nothing material is left for the agent to guess.

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 0%, so the description must carry the burden, and it partially does: the URL must be https and must point at a public agent service, which is not encoded in the schema's generic uri format. It doesn't clarify behaviour for non-https input or whether redirects/ports matter, so it stops short of full compensation.

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 and resource (quick check of a public agent service URL) and then enumerates the exact checks performed: reachability, MCP initialize/tools-list, and x402 402 challenge validity. It explicitly distinguishes itself from buildcheck_report, so an agent can pick between the two without opening either schema.

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?

Names the sibling alternative and the condition that selects it: this is the free quick sample, buildcheck_report gives the full report (OpenAPI, Bazaar metadata, discovery docs). It also discloses the 5-per-hour limit. What's missing is an explicit when-not-to-use (e.g. before paying, or when you already know the service is healthy).

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