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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world behavior, so the safety profile is covered. The description adds one genuine trait beyond the annotations: only 'published' listings are returned, implying unpublished/slug-missed cases behave differently, but it never says what happens on a miss.

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 front-loaded sentence with no filler or redundancy. It is arguably too terse for the job, but nothing in it is wasted.

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?

For a one-parameter lookup with rich annotations and a complete schema this is close to sufficient, but there is no output schema, so the agent gets no notion of what a listing contains or how a missing slug is signalled.

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 description coverage is 100% and there is a single parameter, so the schema fully documents 'slug' including its pattern and length bounds. The description adds only the word 'slug' with no format or resolution semantics beyond that; 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?

Names a specific verb ('Get'), a specific resource ('one published peptide provider'), and the lookup key ('by its slug'), so the agent knows this is a single-record fetch. It does not explicitly contrast itself with search_listings or the list_* siblings, and it uses 'peptide provider' while the tool is named get_listing, which adds mild ambiguity.

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?

There is no when-to-use guidance and no alternatives are named. The phrase 'by its slug' implies you must already know the identifier (rather than searching), but the agent must infer that get_listing is the right choice over search_listings.

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