List replies to a post

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

Even with readOnlyHint=true and openWorldHint=true already present in annotations, the description adds meaningful behavioral context: it is a 'recent-search composite' (indicating the search-based nature and open-world sourcing), and 'Billed per matching post' discloses the cost model. It also adds a social/interaction rule ('confirm required; self-serve only if they summoned you'). No contradiction with annotations.

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?

Three sentences, each earning its place: the composite query, the intended use, and the follow-up/billing/policy caveats. The most identifying information (purpose and mechanism) is front-loaded, and there is no redundant restatement of the title or schema.

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 list tool with three parameters and no output schema, the description covers the essential operational context: what it lists, how the query works, the billing implication, and the required follow-up action. The main gap is that the return shape is not described, but the purpose 'list replies' and the 'recent-search composite' hint make the output reasonably inferable. This is a strong but not exhaustive definition.

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 coverage is only 33%, so the description carries more responsibility for parameters. It clarifies post_id's role via the query fragment 'conversation_id:{post_id}', which adds meaning beyond the bare schema. However, max_results is not explained in the description (though its bounds and self-explanatory name help), and pagination_token is already described in the schema. This partial compensation justifies a middle score.

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 states a specific verb and resource ('List replies to a post') and gives the underlying mechanism ('Recent-search composite: conversation_id:{post_id} is:reply'), making the tool's purpose unambiguous. It also names x_organic_reply as the follow-up step, which indirectly distinguishes it from the many mutation tools in the sibling list, though it doesn't explicitly contrast with other list/search 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?

It gives clear when-to-use context ('Use this to triage comments') and practical constraints ('Billed per matching post'). It also routes the agent to the next tool ('Then reply with x_organic_reply') and states the self-serve policy ('only if they summoned you'), which is actionable guidance. It doesn't explicitly say when NOT to use it or name alternative listing tools, but the guidance provided is concrete.

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