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

Annotations already flag a non-read-only, open-world, non-idempotent call; the description adds real context on top: the message is e-mailed to support, the user receives a copy, a ticket number comes back, and secrets (passwords, card numbers) must not be included. It stops short of stating whether a failed send or a retry produces a duplicate ticket, which matters for a non-idempotent tool.

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-to-use clause, then behavior, then constraints, each as one short sentence with no filler. Every statement (topics, exclusion, confirmation, reference, secret handling) carries actionable information.

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?

Covers trigger, scope, side effects, consent requirement, and the return value (ticket number), and an output schema exists for the full return shape. Nothing needed to invoke it correctly is missing for a 3-parameter mutation tool.

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 100%, so the baseline is 3; the description still adds decision logic beyond the schema — attach a reference only when the message concerns a single letter or order, and keep the message in the user's own words without credentials. That is genuine routing guidance rather than restatement.

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 action (sends the user's message by e-mail to the support team), the outcome (returns a ticket number), and explicitly distinguishes itself from the nearest sibling domain ("Do not use it to write or mail a letter"). An agent can tell this apart from send_letter/prepare_letter without inspecting schemas.

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 the triggering condition (user has a problem or question support must answer), enumerates covered topics, names an explicit exclusion, and adds prerequisites (only send after the user agreed to the text). Alternative routing is covered by the write/mail exclusion.

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