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

Annotations only declare that this is a non-destructive write; the description adds the resource consequence that matters here - it consumes plan keyword slots rather than lookup credits - plus a human-confirmation requirement. It doesn't say what happens to keywords already tracked or whether the slot consumption can be undone.

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?

Three short sentences with the core action front-loaded and no filler. The confirmation sentence is placed after the cost note, which is a slightly odd ordering but still readable.

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?

With an output schema and annotations present, the description covers safety and credit impact well, but for a 4-parameter mutation with zero schema coverage it should at least state keyword count limits, batching, and whether existing tracked keywords are skipped or duplicated.

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 0%, so the description must carry parameter meaning, yet it only explains countryCode's default. projectId, device, and especially the keywords shape (single string vs array up to 500) are left entirely to the bare schema with no format or batching guidance.

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?

"Add keywords to a project" gives a specific verb plus resource, and the name/sibling pair (untrack_keyword) makes the direction of the operation obvious without opening the schema. It stops short of explicitly contrasting itself with research_keywords or untrack_keyword by name.

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?

It states a real precondition ("Confirm the keywords with the user first") and a cost-based routing signal (uses plan keyword slots, not lookup credits), which implicitly separates it from research_keywords. It never names an alternative tool or says when not to use this one.

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