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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false. The description adds significant behavioral context beyond these: it explains the long-polling mechanism ('long-polls for up to 30 seconds by default'), the matching strategy ('uses reply threading, not a sender or subject guess'), and the expected return behavior ('returns with no reply'). No contradictions with 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?

The description is six sentences, each earning its place. It front-loads the core purpose in the first sentence, then quickly covers usage advice, polling behavior, error handling instruction, and matching logic. There is no redundancy or unnecessary detail. The structure is logical and easy to scan.

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 tool's complexity (4 parameters, output schema present), the description covers all essential aspects: when to call, the polling mechanism, timeout behavior, error handling (do not report no reply prematurely), and how matching works. The presence of an output schema reduces the need to describe return values. The description is complete for an AI agent to use this tool 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%, so baseline is 3. The description adds minimal semantic value beyond the schema: it reiterates that 'id' comes from a sendEmail/replyToEmail response (already in schema) and notes that with only the id it long-polls by default. The 'wait' and 'wait_timeout_ms' parameters are adequately documented in the schema. The description does not significantly enhance parameter understanding, so a 3 is appropriate.

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 purpose: 'Wait for the threaded reply to a sent email.' It specifies the action (waiting), the resource (reply to a sent email), and even suggests when to call it (immediately after sendEmail or replyToEmail). This distinguishes it from all sibling tools, none of which are polling or waiting tools.

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: 'Call this immediately after sendEmail or replyToEmail when you expect an answer.' It tells the agent when not to use alternatives ('Do not report that nobody replied or ask the user to check later until this call returns with no reply') and gives specific advice for the 'wait' parameter ('Set wait=false only for a deliberate immediate poll'). This is comprehensive and actionable.

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