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

With no annotations provided, the description bears full responsibility for disclosing behavior. It reveals that results are ordered newest-first and that pagination is supported via a 'before' cursor. However, it does not disclose authentication requirements (despite a 'pass' parameter), potential side effects (though it appears read-only), rate limits, error handling, or the response structure beyond the mention of 'nextBefore.' The disclosure is minimal and insufficient for a tool with this many parameters.

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 extremely concise—two sentences, front-loading the core purpose and pagination hint. It wastes no words and is easily scanned. However, it could be more structured, e.g., separating the primary function from pagination instructions. The brevity is commendable but leaves out crucial details, so it doesn't earn a 5.

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 the tool has 4 parameters, no annotations, and no output schema, the description is far from complete. An agent cannot determine what 'slug' refers to, how 'limit' behaves, or how to construct the 'before' cursor beyond the vague hint. The response format is unspecified, and the meaning of 'nextBefore' is not explained clearly. The tool is simple in concept but the description does not equip the agent to call it correctly without further schema inspection.

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 description coverage is only 25% (only 'pass' has a description), so the description must compensate. It does not. The description mentions 'before' and 'nextBefore' but does not explain the parameters 'slug,' 'limit,' or 'before' in detail. It fails to clarify that 'slug' identifies the room, 'limit' caps results, and 'before' is a pagination cursor. No parameter semantics are added beyond what the schema already states.

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 clearly states the tool returns 'the thread index of one room, newest first.' This identifies the resource (thread index of a single room) and the ordering. It also mentions pagination with 'before' from 'nextBefore,' which further clarifies its function. While it lacks a verb like 'list,' the intent is unambiguous and distinct from sibling tools like 'boards' (plural rooms) and 'thread' (single thread).

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 provides no explicit guidance on when to use this tool versus alternatives. It does not mention that this is for viewing threads in a specific room or contrast it with 'boards' for multiple rooms or 'thread' for a single thread. There is no indication of prerequisites or exclusions. The only contextual hint is 'one room,' but this is not elaborated.

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