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

Annotations declare destructiveHint=true and idempotentHint=true, but the description narrows that blast radius concretely: already-sent messages stay sent, the contact is not unsubscribed or blocked, and other sequences/automations keep running. It also adds the 'Confirm with the user first' guardrail and source-of-truth for the contact id, which the annotations cannot express.

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-loads the action and its scope, then exclusions, then provenance of the id, then the confirmation requirement. Dense but every clause carries decision-relevant information with no filler.

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 destructive-but-scoped mutation with no output schema, the description supplies the trigger conditions, the non-effects, the alternative tool, and a confirmation step, while annotations cover idempotency and safety. Nothing an agent needs to call this correctly 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 description coverage is 100%, so contactId, sequenceId and idempotencyKey are already documented, including the retry semantics of idempotencyKey. The description only adds that ids come from list_contacts or get_contact, which marginally overlaps the schema; baseline 3 is appropriate.

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 ('Stop a drip sequence for ONE contact'), and the scope qualifier 'ONE contact' immediately separates it from bulk or contact-level operations. It also distinguishes itself from update_contact by name, so an agent can route without opening either 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?

Gives explicit trigger scenarios ('someone asks to stop getting those messages, already bought, or was enrolled by mistake'), an explicit exclusion ('It does not unsubscribe or block them, and other sequences and automations keep running'), and names the alternative tool (update_contact) with the exact fields that would apply. Nothing is left to inference.

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