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

Annotations already declare readOnlyHint=false, destructiveHint=false and idempotentHint=true, but the description goes well beyond them: atomicity, the in-flight-message caveat that must not be over-promised, contacts retaining sequence position, released_units accounting, exact 409 semantics, the dual module gating for writes vs reads, and the fact that the action is logged. This is unusually rich behavioral disclosure that the annotations alone could not supply.

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 the key caveat, and nearly every sentence carries operational value. It is nevertheless a very long block: the verbatim quoted 409 message and the maintainer-confirmation aside could be trimmed without losing decision-relevant content.

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?

There is no output schema, so the description must carry return semantics, and it does: on success the drip returns with Status paused, PausedAt set, and released_units explained including the '0 is correct' false-negative warning. Error, gating and side-effect behavior are all covered, leaving nothing an agent needs to call this correctly.

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?

With a single parameter at 100% schema description coverage, the schema already documents drip_token as a UUID v4 of an active drip. The description reinforces the 'must be ACTIVE' constraint but adds no format or syntax detail beyond the schema. Baseline 3 is appropriate when the schema does the heavy lifting.

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 (pause) and resource (drip campaign), and immediately carves out the sibling: resume_drip is named as the reversal and the create/edit/activate/delete family is explicitly declared out of scope. An agent can distinguish this from pause_campaign, pause_sweepstakes and resume_drip without opening a 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?

Explicitly states the precondition (only an ACTIVE drip can be paused), the failure behavior for every other status, and the correct agent reaction (read the 409 message back, do not retry). It also routes the agent away from a non-existent create tool and names resume_drip as the alternative action, so both when-to-use and when-not-to-use are covered.

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