read_messages

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

States 'Read-only with no side effects', and describes what each message includes. No annotations provided, so description carries full burden; it adequately discloses read-only nature and output detail.

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?

Four concise sentences with no wasted words. Front-loads purpose and immediately gives key details.

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 5 parameters with full schema coverage and output schema present, the description covers purpose, output format, prerequisite, and alternative tool sufficiently without needing to repeat schema details.

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%, so baseline is 3. The description adds minimal extra meaning beyond the schema (e.g., chat_name must be exact from list_chats), but does not significantly enhance parameter understanding.

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?

Description clearly states 'Read messages from a single Signal chat' with verb and resource, and distinguishes from sibling 'search_messages' which finds messages by keyword across chats.

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?

Provides prerequisite ('Requires an exact chat name from list_chats') and an alternative ('Use search_messages instead'), but does not explicitly exclude other inappropriate use cases.

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