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

With annotations only declaring destructive/not-idempotent/non-read-only, the description carries strong extra context: nothing sends until launch in draft, active/paused campaigns enrol immediately, only REVEALED-email creators qualify, others return as excluded, dm_only have no email, and the approval_token guard returns an approval_required error. This is exactly the behavioral depth annotations cannot provide.

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?

Dense but front-loaded with the verb and resource, then ordered by behavioural importance (draft, enrolment, eligibility, guard). The closing 'dashboard guardrail' sentence earns its place as a scope statement, though the prose is heavier than strictly necessary.

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 complex, non-idempotent, destructive mutation with no output schema, the description covers the mutation semantics, eligibility filtering, error/approval flow, and downstream scheduling effects. Nothing an agent needs to call it 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 coverage is 100% so the baseline is 3, but the description adds real meaning: creator_ids eligibility rules (revealed email, no opt-out/bounce) and the approval_token round-trip (error response, then re-call with token). It goes beyond the schema's one-line parameter docs without restating them.

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 ('Add creators to a campaign') and immediately distinguishes the operation from a plain write by explaining draft-growth vs active/paused enrolment. An agent can tell this apart from siblings like add_websites_to_campaign or launch_campaign 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 anchors the tool to the dashboard 'Add to campaign' action, spells out when it applies (draft vs active/paused), and gives a real exclusion: 'Campaigns written for websites refuse creators.' Alternatives and preconditions are covered.

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