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

Annotations already declare non-read-only, non-idempotent, non-destructive behavior. The description usefully adds the daily send-cap constraint, which annotations cannot express, but it does not say what happens when the cap is hit or whether repeated calls create duplicate records despite idempotentHint=false.

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?

Two short sentences that front-load the action and then the prerequisite and constraint. 'Daily send cap still applies' is slightly elliptical but earns its place as the only behavioral caveat.

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 no output schema, the description covers the prerequisite, the side effect (marks a message as sent) and the rate cap, while annotations cover the safety profile. It stops short of describing duplicate handling or downstream pipeline effects.

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% with all four parameters described, so the schema carries the parameter burden. The description adds a small amount by tying 'tactic' and 'next_step' back to the schema returned by get_message_prompt, but no field formats or constraints beyond that.

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 – recording a drafted message as sent to a prospect – which is clear on its own. It does not distinguish itself from the sibling mark_sent, so an agent must guess which of the two records a send in which situation.

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 an explicit prerequisite ('Use after get_message_prompt') and an operating constraint ('Daily send cap still applies'), which is real sequencing guidance. It omits any when-not guidance and says nothing about how it differs from mark_sent or upload_draft.

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