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

Goes well beyond the annotations: max 100 contacts per call, only awaiting_launch emails are eligible, prior approvals are cleared, and queued/sending/sent/skipped contacts surface as not_editable and are left untouched. The non-idempotent side effect (approval clearing) is disclosed even though the idempotentHint only says 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?

Front-loaded with the core action and eligibility, then rules, then follow-up. It is long, but nearly every sentence carries operational information (state handling, copy rules, return shape, next call). Minor trimming possible in the RankParse recovery explanation.

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 and a nontrivial eligibility state machine, the description covers eligibility, side effects, per-contact result types (updated, not_found, not_editable, invalid), and the required follow-up. Nothing an agent needs to call it safely is missing.

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, but the description adds real semantics: contacts are matched by email address and the address itself never changes, plus hard constraints on subject (2-5 words, ≤500 chars) and body (≤10,000) that are absent from the schema. It stops short of per-item detail, but that is already in the schema.

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 ('Rewrite the subject and body of contacts that are already in a campaign, in that same campaign') and explicitly differentiates itself from outreach_add_contacts and outreach_create_campaign. An agent can pick this tool without opening any sibling schema.

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?

Names the triggering user request ('change or redo email copy'), the exclusion ('do NOT create a new campaign'), and the alternative to avoid ('do not try outreach_add_contacts'). It also prescribes the recovery path for queued emails (Unapprove in RankParse) and the required follow-up call (outreach_launch_campaign).

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