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

Annotations already declare this is a non-read-only, non-destructive mutation, so the safety profile is covered. The description adds real value with the PATCH semantic ("fields you leave out keep their value"), but says nothing about array replacement (emails/mailboxes), permission requirements, or what error occurs when the campaign is not paused/draft.

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, zero filler, with the mutation scope and precondition front-loaded. Nothing here could be cut without losing information.

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 5-parameter mutation with 20% schema coverage and no output schema, the description is too thin: it neither compensates for undocumented parameters nor describes failure modes (active campaign, invalid ids). Annotations cover only the safety profile.

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 only 20% (only campaign_id is documented) and the description names none of the five parameters. The omit-keeps-value sentence conveys optionality semantics, but name, emails, mailboxes and daily_limit — including whether arrays replace or merge — remain undocumented in both places.

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 ("Edit a ... campaign") and adds a precondition ("paused or draft") that separates it from create_campaign, get_campaign, pause_campaign and start_campaign. It doesn't explicitly name those siblings, so it falls just short of a 5.

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?

"Edit a paused or draft campaign" implies the usage condition, but the agent is left to infer what to do if the campaign is active (pause first? use start_campaign instead?) and no sibling is named as an alternative. Precondition is stated; routing guidance is missing.

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