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

With no annotations provided, the description carries the full burden of behavioral disclosure. It discloses that measurement is tied to the action completion date, that publishedUrls replaces the existing list (with a warning to retain entries), and that existing measurement dates cannot be overwritten. It also notes the required permission (actions.write). These are significant behavioral details that an agent needs to know before calling this mutation tool. It does not mention reversibility or idempotency, but the coverage is solid.

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?

The description is succinct and front-loaded with the core action. Each sentence adds essential information: the action itself, the human approval prerequisite, the measurement timing nuance, the replacement behavior for publishedUrls, the immutability of existing dates, and the permission requirement. There is no fluff or redundancy; every word earns its place.

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 mutation tool with four parameters, no output schema, and no annotations, the description covers key contextual aspects: prerequisites (human approval), behavioral details (measurement timing, list replacement, immutability), and permissions. It does not describe return values or error conditions, but without an output schema these may not be critical. The description is adequate for an agent to invoke the tool correctly, though it could mention what happens if the action is not completed or if the URL already exists.

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 compensate. It specifically explains the semantics of publishedUrls (it replaces the list and existing entries must be retained), which is valuable. However, it does not explain the semantics of actionId, url, or changeEventId beyond the obvious from names and context. Since the schema has no descriptions, the description could have elaborated on these parameters, especially changeEventId, but it covers the most complex one. It adds partial value but not full compensation for the zero coverage.

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?

The description opens with a specific verb and resource ('Attach a published URL to a completed action'), clearly stating what the tool does. It distinguishes itself from the many 'get_', 'list_', and 'update_' siblings by focusing on the unique action of attaching a URL to a completed action. No other sibling covers this operation, so purpose is unambiguous.

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?

The description provides some usage context: it instructs to 'Obtain human approval first' and clarifies that measurement starts at the completion date, which are important prerequisites and behavior notes. However, it does not explicitly mention when to use this tool versus alternatives (though no direct alternatives exist), nor does it state when not to use it. The guidance is helpful but not exhaustive regarding selection criteria.

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