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

With only readOnlyHint=false in the annotations, the description carries the full burden of behavioral disclosure and excels: it states nothing is sent, watermarked drafts are refused, the user must unlock the email, and the tool reports unsupported grants. It also tells the agent what it will receive (a link to the draft).

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?

Every sentence earns its place: the core action, the critical non-sending guarantee, the unlock precondition, and the grant limitation. The description is compact yet dense with necessary information, and the most important fact (nothing is sent) appears early.

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 mutation tool with 4 parameters and no output schema, the description covers prerequisites, failure conditions, and return value. An agent has enough information to call the tool correctly and to anticipate when it should not be called.

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?

The input schema already covers all parameters at 100%, so the baseline is 3. The description adds useful context by linking artifact_id to generate_email and by noting recipients are the ones the user named, but it does not significantly expand on the schema's parameter meanings.

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 verb and resource: put a generated email artifact into the user's Gmail drafts. It adds precise scope by requiring an artifact_id from generate_email and says explicitly that nothing is sent. This distinguishes it from generic draft creation tools like create_gmail_draft.

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 gives clear context for when the tool can be used: only for unlocked generated emails and only on mailboxes connected under a legacy modify grant. It does not explicitly mention alternatives, so it stops short of a 5, but the constraints are concrete and actionable.

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