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

With no annotations provided, the description carries the full burden and adds useful behavioral context: 'FREE' indicates no cost, 'Lists every product' indicates exhaustive scope without filters. It also communicates a read-only discovery purpose. No contradictions with annotations exist since none are present.

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 two sentences, front-loading the most important fact ('FREE') and stating the core function and purpose in an efficient manner. Every word is informative, with no fluff or repetition.

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 zero-parameter tool with an output schema, the description fully covers what the tool does, what data will be returned (endpoint, price, summary), and when to use it. The output schema handles return structure, so the description is complete for an agent deciding to invoke this tool.

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 input schema has 0 parameters, so the baseline is 4. The description adds a small amount of semantic value by stating there is no filtering ('every product'), reinforcing that no parameters are needed. It does not describe parameters because none exist.

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 the specific verb 'Lists' with resource 'every product of this data shop' and details exact contents (HTTP endpoint, price in USDC, one-line summary). This clearly distinguishes the catalog tool from sibling data lookup tools, which serve specific data services rather than an index of them.

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 explicitly states when to use the tool: 'Use it to discover capabilities before paying.' This provides a clear usage context, though it does not explicitly mention alternatives or exclusions. It effectively guides the agent to use this first as a discovery step before selecting a specific sibling tool.

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