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

The description adds little beyond the annotations: 'Attaches' is consistent with readOnlyHint=false, but it does not explain idempotency implications, duplicate-handling behavior, or any side effects. The openWorldHint and idempotentHint are left unexplained, so the description carries minimal behavioral value.

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, front-loaded sentence with no filler words. It is appropriately concise but not quite a 5 because it omits supporting context that would make the definition more independently useful.

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 mutation with an output schema and fully documented parameters, the description is minimally workable. However, it lacks usage guidance, behavioral caveats, and differentiation from sibling tools, so the agent must rely heavily on naming conventions and structured metadata.

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 'name' and 'subjectId' already have descriptive schema text. The description itself adds no parameter-level detail, so the baseline score of 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?

The description states a specific verb ('Attaches') and resource ('a surname to an SMI subject'), making the core operation clear. It distinguishes itself from sibling add_subject_address/email/phone tools by naming the surname as the object, though it does not explicitly contrast with add_subject_alias or update_subject.

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?

There is no guidance on when to use this tool versus alternatives, no exclusions, and no prerequisites. Usage is only implied by the tool name and the single action phrase, with no mention of when to prefer smi_add_subject_alias or smi_update_subject.

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