message_list

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

Description accurately reflects read-only nature (consistent with annotations) and clarifies scope ('full history, not just unread'). Annotations already provide readOnlyHint=true and destructiveHint=false, so description adds limited behavioral context beyond this distinction.

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?

Extremely concise: the first sentence captures purpose, second guides usage, and the parameter list is cleanly formatted. Every sentence adds value with no redundancy.

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 the presence of an output schema (so return values need not be described), the tool definition fully covers purpose, usage, parameter details, and alternative tool. It is contextually complete for an AI agent to select and invoke 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 description's parameter explanations are identical to the schema's descriptions. No additional semantic value beyond what the schema already provides.

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 'List all messages sent to or from you (full history, not just unread).' Verb and resource are explicit, and it distinguishes from message_inbox (unread-only).

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 states when to use (reviewing past conversations, checking missed messages, auditing) and directly names the alternative tool: 'For unread-only, use message_inbox() instead.'

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