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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds genuine value beyond that by detailing the markdown output format and its structural sections, plus equivalence to the .md and HTML endpoints. It omits auth/rate-limit nuances but the core behavioral profile is well disclosed.

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?

A single dense sentence that front-loads the payload ('One agent in full') and then enumerates what it contains. No filler, though the clause about being identical to the .md/HTML page is somewhat tangential.

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 correctly carries the return-value burden and describes the content structure in detail. The single required parameter is documented in the schema and annotations cover safety, leaving little an agent needs that 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?

Only one parameter, and the schema fully documents it as the listing slug sourced from search_listings or the URL. The description itself adds no slug syntax or format detail, so the baseline 3 for high schema coverage 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?

The description makes clear this returns a single listing in full, and even specifies the content shape (summary, all questions with answers, vendor wording, proof URL). It does not explicitly contrast itself with sibling tools like search_listings, so differentiation is inferred rather than stated.

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: fetch one listing by its slug. The note that the result is 'identical to /{slug}.md and to the HTML page' gives the agent an equivalence hint, but there is no explicit when-to-use or when-not-to-use guidance versus search_listings or compare_listings.

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