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

No annotations are provided, so the description carries the behavioral burden. It communicates that the operation is a read-only fetch and that the result contains every field carried by the store's feed, which is useful behavioral context. It does not mention not-found behavior or data freshness, but for a simple get-by-id tool the stated behavior is largely sufficient.

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, front-loaded sentence with no filler. Every part adds information: the operation, the target, and the completeness guarantee. It is appropriately sized for the tool's low complexity.

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?

The tool is simple: one required parameter and no output schema. The description tells an agent what it will receive and what the input means. It does not enumerate the feed fields or define the id format, but given the low complexity and clear sibling set, the description is nearly complete.

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 schema has 0% description coverage, so the description must compensate. It does identify id as the lookup key, but it adds little beyond the schema property name: it does not specify id format, source, or uniqueness assumptions. For a single required string parameter this is adequate but minimal.

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 uses a specific verb and resource: 'Fetch one product by its id.' The additional clause 'with every field the store's feed carries' clarifies that this returns the complete product record, which distinguishes it from browsing, searching, or recommending actions among the sibling tools.

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 clearly establishes that this tool is for retrieving a single product when its id is known. It does not explicitly mention alternatives or exclusions, but the contrast with browse_products and search_products is strongly implied. An agent can reasonably infer when to choose this tool over list-oriented siblings.

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