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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds useful behavioral context: it returns both results without ranking or personalized advice, and implies no cost or public access. This goes beyond what annotations provide, though it could mention rate limits or error behavior.

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 zero filler. It leads with the usage condition and immediately clarifies key behavioral constraints (no ranking, no personalization).

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 3-parameter tool with no schema descriptions, the description is insufficient. An agent needs to know how to specify the calculator (likely via an ID from a list tool) and what constitutes valid input JSON. The output schema exists, so return format isn't required, but the input contract is underspecified.

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?

With 0% schema description coverage, the description must compensate by explaining the parameters. It only vaguely implies 'two inputs' but does not clarify what 'calculator' should be (e.g., an identifier from list_public_calculators) or the expected format of the input JSONs. The names firstInputJson and secondInputJson hint at JSON, but no format details are given.

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 clearly states it runs two inputs through the same free public calculator and returns both results without ranking, which distinguishes it from run_public_calculator and other siblings. It specifies the verb, resource, and scope in one sentence.

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?

Provides an explicit 'Use this when...' condition, indicating it should be used when two inputs need to be run through the same calculator. However, it does not explicitly mention when not to use it or point to an alternative like run_public_calculator for single runs, leaving some inference to the agent.

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