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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the bar is lower. The description still adds real value by disclosing the output nature (a fixed explanation plus a suggested alternative calculation) and a privacy constraint: no request text, names, identifiers, or document content are accepted. It doesn't mention determinism of the fixed text beyond idempotentHint, but the important behaviors are covered.

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 sentences, front-loaded with the core behavior, followed by the scope enumeration. No filler; every clause carries scope or constraint information.

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?

An output schema exists, so return values need no explanation. For a single-parameter refusal tool with full annotation coverage, the description supplies everything an agent needs: what it does, which categories qualify, and the no-PII input constraint.

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 the enum values are enumerated in the schema, so the baseline is 3. The description's restatement that only the category is accepted and never user/borrower/document data largely duplicates the schema's own parameter description rather than adding new semantic detail per enum value.

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 and outcome (returns a fixed explanation that the request is out of scope, plus an alternative calculation) and enumerates the exact categories it covers. That enumeration makes it trivially distinguishable from the calculate_* and compare_* siblings.

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 category list functions as an explicit when-to-use test: approval/underwriting, recommendations, borrower documents, rates/rules, external actions, other. It does not explicitly say 'use the calculate_* tools instead for supported requests', but the 'with a calculation it can do instead' clause implies the routing. Clear context, no explicit exclusions.

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