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

Annotations already provide readOnlyHint=true and destructiveHint=false, so the agent knows it's a safe read operation. The description adds the constraint that the profile must be 'registered', which is useful context but does not significantly expand on behavioral traits.

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 a single 9-word sentence that front-loads the verb and resource. Every word earns its place, with no wasted text. It is optimally concise for a simple retrieval tool.

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?

Given the tool has only 2 parameters with strong schema descriptions and an output schema, the description is sufficient for a simple fetch operation. It covers the core purpose, though it does not mention handling of non-existent profiles or default behavior for optional namespace.

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?

The input schema has 100% coverage with descriptions for both parameters. The tool description does not add new meaning beyond what is already in the schema, merely restating that it fetches by namespace and agent_id. Baseline score of 3 is appropriate.

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 clearly states the action 'fetch' and the resource 'one registered UCP profile' by the criteria 'namespace and agent_id'. It distinguishes itself from sibling tools like register_ucp_profile (which is for creating) and shopping tools (different domain).

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 implies this tool is for retrieving a specific profile when you have the agent_id and optionally namespace. It does not explicitly state when to avoid it or mention alternatives, but the purpose is clear enough for an agent to infer usage context.

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