Trả lời thư trong hộp

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

Annotations already establish this as a non-read-only, open-world, non-idempotent write, and the description adds real value beyond that: it sends from the inbox address, sets In-Reply-To/References headers for threading, requires text or html, and defines a human-escalation policy. It omits failure/rate-limit behavior and whether a sent reply can be recalled.

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?

Front-loads the when and how, and every clause earns its place (threading, body requirement, escalation rule). The bilingual duplication is efficient but adds some length.

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 send-type tool with no output schema, the description covers the key concerns: threading, sender address, body requirement, and human escalation. Missing return/error behavior is minor given the annotations already signal a non-idempotent write.

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 coverage is 0%, so the description must carry parameter meaning. It clarifies that text or html is required (a real constraint not visible in the schema, where both are individually optional) and implies message_id drives threading via In-Reply-To/References, but inbox_id and message_id semantics are left unexplained.

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?

States a specific verb and resource ('reply to an inbox message in-thread'), which distinguishes it from the generic mail_send sibling by emphasizing the in-thread reply scope. It does not explicitly name mail_send as the alternative, so it falls short of full sibling differentiation.

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?

Gives clear context for use ('when the agent replies to a customer') and an explicit exclusion — hard-to-revoke actions like promising prices or transferring money should be escalated to a human rather than sent automatically. It stops short of naming the alternative tool (e.g. mail_send) for non-inbox sends.

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