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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds only that the grade comes from the 'score_v1 rubric' and mirrors an HTTP endpoint, with no note on return format or limits. With annotations carrying the load, a 3 is appropriate.

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?

Two short, front-loaded sentences with no filler. The endpoint mapping is arguably extraneous but compact enough not to harm readability.

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?

A simple read-only tool with one parameter and no output schema, so the burden is low. Still, the description never indicates what an 'explanation' contains, leaving the agent to guess the response shape for a tool whose entire value is its output.

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 coverage is 0% and there is one required parameter. The description merely restates the parameter name ('delta_pct') without explaining what the delta is measured against, expected units, or valid range. It does not compensate for the total lack of schema documentation.

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?

States a specific verb and resource: 'Explain the score_v1 rubric grade'. The agent knows it retrieves an explanation rather than computing a score. It does not differentiate from the sibling score_deal, which appears to be the scoring counterpart.

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 only contextual hint is 'Same as POST /api/explain', which maps to an API but says nothing about when to reach for this tool versus score_deal or health. No prerequisites, no when-not-to-use guidance.

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