Chat Summary

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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true, so the safety profile is clear. The description adds context by explaining the return structure (chat and messages objects) and that the output is human-readable. No contradictions exist. While it doesn't go beyond what annotations provide for safety, it adds value in output transparency.

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 highly concise with no wasted words: a one-sentence purpose, a one-sentence usage note, and clearly formatted Args and Returns sections. Every sentence serves a purpose, making it easy for an agent to parse.

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?

Despite lacking an output schema, the description provides a detailed textual description of the return value (chat info and messages with sender, body, timestamp, type). This fully compensates for the missing schema, and the tool's simplicity (2 parameters) means no further information is needed.

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 both parameters have schema descriptions. The description's 'Args' section repeats the schema descriptions verbatim without adding new information. Thus, the description adds no additional semantic value beyond the schema, meeting the baseline for high coverage.

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's purpose: 'Get a readable summary of recent messages in a WhatsApp chat, including sender names and timestamps.' It also distinguishes from siblings by explicitly mentioning alternatives (whatsapp_read_messages for structured data, whatsapp_search_messages for full-text search), making the purpose unambiguous.

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 explicit usage guidance: 'This is optimized for readability — use whatsapp_read_messages for structured data with filtering, or whatsapp_search_messages for full-text search.' This clearly tells the agent when to use this tool versus alternatives, fulfilling the highest standard.

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