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

Annotations only say readOnlyHint=false and destructiveHint=false; the description adds the material context that the operation is confined to queued (pending/awaiting-approval) emails, which explains why a "Remove" action is flagged non-destructive and reassures the agent no sent mail is touched. It does not cover failure behavior or whether the email re-enters approval, but with annotations present the bar is lower.

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-loaded with the action, then preconditions, then scope in three tight sentences with no filler. Minor waste from the id sentence, which duplicates the schema text almost verbatim.

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 two-required-param mutation with no output schema and thin annotations, the description covers scope, the state precondition, and where the attachment id comes from. It leaves open whether the underlying file is deleted or merely unlinked and what happens when the email is already sent, which keeps it short of complete.

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 baseline is 3. The description adds real meaning for recipient_email (it must identify a queued email in pending/awaiting-approval state), but its explanation of id largely restates the schema's own "the attachment's `id` from the queue status read," and on_behalf_of is not mentioned at all in the description.

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 ("Remove a file already attached to a queued outreach email") and bounds scope with "Email queue only, mirroring attach_to_outreach," which lets an agent place it relative to the attach/list/read attachment siblings. It stops short of naming a true alternative, but the inverse-relationship framing does most of the differentiation work.

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 a concrete precondition: recipient_email targets a queued email in the pending or awaiting-approval state, plus an explicit scope limit (email queue only). No exclusions or alternative tools are named for the case where the email is not queued, so it is clear context rather than full when/when-not guidance.

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