list_messages

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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true. The description adds valuable context: 'reads local cache; works while disconnected' and 'returns a human-readable formatted text block', going beyond 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, front-loaded with key attributes (local cache, offline, search), then filter summary, then alternative tools, then return format. No wasted words.

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 10-parameter tool with no output schema, the description sufficiently explains what the tool does, the filtering capabilities, and return format. Lacks explicit mention of pagination behavior but the schema's page/limit parameters and the phrase 'page through' imply it.

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?

Input schema covers all 10 parameters with descriptions (100% coverage). The description briefly restates filters ('filtering by chat, sender, time range, and substring; can include surrounding context messages') but adds little new meaning beyond the schema.

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 reads local cached WhatsApp messages, searches and pages through them with various filters, and names sibling tools for alternative use cases (get_message_context, request_sync), distinguishing its purpose.

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?

Explicitly tells when to use this tool (searching/filtering messages) and when to use alternatives: 'Use get_message_context to expand around a single known message ID, or request_sync to backfill missing history.' Also notes it's read-only with no side effects.

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