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

Annotations already declare destructive=true, idempotent=true, openWorld=true and readOnly=false, so the description doesn't need to restate the mutation profile. It does add genuinely new behavior: the change is mirrored to the ad network on a best-effort basis, implying possible propagation lag or partial failure, plus the API-type-campaign constraint. It stops short of saying what happens if the site isn't currently blacklisted or what auth/plan requirements apply.

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?

A single dense sentence with the action front-loaded and the caveat (best-effort network mirroring) placed as a parenthetical qualifier. No filler or redundant restatement of the title.

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 two-parameter mutation with no output schema and rich annotations, the description covers the core action, its scope restriction, and the external side effect. The remaining gap is failure/error semantics, which is minor at this complexity level.

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% and both parameters are documented there (id = Campaign id, site = Placement/source id to unblock). The description only echoes the placement concept and adds no format, ID-type, or source-specific detail beyond the schema, so the baseline 3 applies.

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 (remove one placement from a campaign's blacklist) and scopes it to API-type campaigns, which implicitly distinguishes it from the sibling block_campaign_placements. It never names that sibling, so the differentiation is inferred rather than stated.

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?

Usage is only implied: an agent can infer this is the inverse of blocking, but there is no explicit when-to-use/when-not guidance, no statement that the placement must already be blacklisted, and no mention of get_campaign_blacklist as the way to verify state first.

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