Chat Activity

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

Annotations already cover safety (readOnlyHint, idempotentHint, destructiveHint=false), so the repeated "Read-only with no side effects" adds little. The description does add meaningful behavior by explaining the ranking and the computed fields (last message date, last reply date, unanswered inbound count), though it leaves sorting tie behavior and pagination unstated.

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 short and front-loaded: it states the primary purpose first, then the safety profile and usage guidance. Every sentence contributes to selection or interpretation.

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?

With rich annotations, a fully described parameter, and an output schema present, the description need not explain return values in detail. It still provides enough purpose, usage, and behavioral context for an agent to call the tool correctly.

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 100%, and the single limit parameter is already fully documented in the schema. The description does not add syntax or filtering semantics for limit, so the baseline of 3 is appropriate.

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 gives a specific verb and resource ("List Signal chats") and adds the ranking criterion (recent activity) plus the fields surfaced. It explicitly distinguishes itself from list_chats, so an agent can select it without opening the schema.

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 states the intended use case ("identify chats that need a response") and names the alternative (list_chats) with the condition that selects it (general chat directory with message previews). This is explicit when-to-use guidance.

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