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

Annotations already indicate readOnlyHint and openWorldHint. The description adds that ineligible retailers are omitted entirely (fail-closed) and describes it as a 'descriptive directory only', providing behavioral context beyond annotations. No contradictions.

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?

Two concise sentences. The first sentence delivers the core purpose, the second adds behavioral nuance. No extraneous information. Front-loaded efficiently.

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?

Given no output schema, the description could be more explicit about the return format (e.g., list of retailer IDs and names). It calls it a 'descriptive directory', which is somewhat vague. However, for a simple list tool with good annotations, it is marginally adequate.

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?

There are zero parameters, so schema coverage is 100%. The baseline for 0 parameters is 4. The description adds no parameter-specific details, which is acceptable given no parameters exist; it focuses on what the output represents.

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?

Description clearly states the tool lists currently eligible/visible retailers. The verb 'list' and resource 'retailers' are specific, and the qualifier 'eligible/visible' adds precision. Indirectly distinguishes from siblings like get_market_snapshot or search_offers by focusing on a simple directory listing.

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 implies usage: when you need the directory of eligible retailers. However, it does not explicitly state when not to use it or suggest alternatives like get_market_snapshot for market-level data or search_offers for filtered results. Guidance is minimal.

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