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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds the return shape ({input, result, decimal}) but nothing else behavioral — no note on divide-by-zero handling, denominator constraints, or defaults for the optional operands.

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 tight, front-loaded sentences with no filler; the operation list leads and the return/cross-reference follow. The return-value clause is slightly redundant given an output schema exists, costing a little density.

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?

With 5 fully documented parameters, an output schema, and complete annotations, the description is close to sufficient. It could still note that num2/den2 are optional (so 'simplify' works with a single fraction) and that this tool overlaps calculate_fraction_operations.

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 of operations is fully documented in the schema, so the description's list of operations ('add, subtract, multiply, divide, simplify') merely repeats structured data. Baseline 3 is appropriate when the schema already carries parameter meaning.

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+resource ('Perform fraction operations') and enumerates the supported operations, so the tool's function is unambiguous. However, it does not distinguish itself from the near-identical sibling calculate_fraction_operations (nor from calculate_ratio_simplify), leaving the agent unable to tell why it would pick this one over that one.

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 statement of when to use this tool versus the duplicate-looking calculate_fraction_operations sibling, nor any prerequisites. 'See list_bundles for related math calculators' is a cross-reference to a discovery tool, not usage guidance for this calculator.

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