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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false, and openWorldHint=true, so the description doesn't need to restate those. The description adds minimal behavioral context beyond the annotations—it doesn't mention whether the URL replaces existing URLs, whether duplicates are allowed, or what the response contains. The output schema exists, which covers return values, but the mutation semantics are not disclosed.

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, efficient sentence that front-loads the action. It is appropriately sized for a simple tool, though it could have added a brief note about the URL's purpose or the distinction from sibling URL tools without becoming verbose.

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 simple two-parameter tool with a full output schema and annotations, the description is mostly adequate. However, given the large sibling set of similar 'add' tools, a brief note on when this tool is appropriate versus the URL-specific siblings would improve completeness. The lack of any behavioral detail about the mutation (e.g., append vs. replace) is a minor gap.

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%, so the schema already documents both parameters. The description adds no additional parameter meaning beyond what the schema provides, which is the baseline 3 per the rubric.

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 states a specific verb ('Attaches') and resource ('a url to an SMI subject'), which clearly identifies the action. It doesn't explicitly distinguish itself from sibling tools like smi_add_subject_employee_url or smi_add_subject_relationship_url, but the resource and parameter schema make the core purpose clear.

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 usage context by mentioning 'SMI subject' and the schema notes the subjectId comes from a prior smi_get_subject or subject-enrichment call. However, it doesn't explicitly state when to use this tool versus the sibling URL-adding tools (e.g., smi_add_subject_employee_url, smi_add_subject_relationship_url), leaving the agent to infer the distinction.

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