List Chats

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so 'Read-only with no side effects' is largely redundant. The description does add non-annotation context: the data source (local desktop database) and the result ordering (most recent message first), which affects how an agent interprets results. No auth or pagination caveats, but nothing contradicts 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?

Front-loaded with the core action and scope, followed by return contents and sibling routing. Efficient overall, though 'Read-only with no side effects' duplicates the annotation block and doesn't add signal.

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?

Output schema exists so return values needn't be described, annotations cover the safety profile, and schema fully documents both parameters. The description contributes the remaining needs: data source, sort order, and sibling routing. Nothing an agent needs to call it correctly is missing.

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 100% with defaults and ranges documented for both limit and query, so the schema already does the work. The description mentions no parameter behavior at all (e.g., how limit interacts with sorting, or whether query matches phone numbers), so the baseline of 3 is right.

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 verb and resource ('List direct and group Signal chats from the local desktop database') with scope qualifiers: local database, sorted by most recent message. Clearly separable from list_groups, which it names as a different scope.

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?

Gives explicit when-to-use ('discover exact chat names before calling read_messages or search_messages') and an explicit when-to-use-alternative ('Use list_groups instead when you need group_id values for send_message'). This routes the agent between siblings with no inference required.

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