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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuinely new context: it returns ALL ranking types along with their definitions, and it mirrors a specific public endpoint, which tells the agent the payload is a static enumeration rather than a personalized query. No gaps beyond return formatting.

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?

One sentence, front-loaded with the 'Discovery:' cue, then the enumeration of data covered, then the endpoint reference. No filler, no restatement of the name.

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, non-destructive read with no output schema, the description covers what data comes back (all ranking types plus their definitions) and its provenance. It does not describe the response envelope or ordering, but with no output schema that is a minor omission rather than a blocking gap.

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 tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The description correctly implies the call is parameterless by framing it as a full enumeration of all rankings.

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?

States a specific resource (every Promo Board ranking) and enumerates the ranking families it returns (most expensive active link, highest takeover, lifetime spend, most renewed, trending, category leaders), so an agent can tell this is the aggregate leaderboard rather than a listing lookup. It stops short of naming a sibling tool it supersedes or replaces, which keeps it from a 5.

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 'Discovery:' prefix implies the intended use — fetch the catalog of rankings before drilling into a specific one — and the REST-endpoint equivalence gives a mental model. However, there is no explicit when-not guidance, no mention of whether promo_get_listing or promo_get_featured is the follow-up, so routing is left to inference.

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