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

Annotations declare readOnly and closed-world, and the description is consistent with both while adding real substance: the exact return payload (headline, supporting figures, reading, link) and the silent fallback to example values for missing inputs — a default an agent could otherwise misread as an error.

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?

Four dense sentences, front-loaded with purpose and return shape, then the default-behavior and input-format caveats. No filler and no restatement of the title.

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?

Covers discovery (list_calculators), invocation defaults, unit conventions for the two ambiguous input kinds, and the response shape. With no output schema present, naming the returned fields is exactly the gap the description needed to close.

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 100%, so the baseline would be 3, but the description earns extra credit by documenting the free-form `inputs` map's conventions: percents as points (15 = 15%) and choices as option index. Those conventions are invisible in the schema, where inputs is just an anyOf of number/string/null.

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 ("Runs one calculator from list_calculators on your numbers") and enumerates exactly what comes back: headline result, supporting figures, a one-sentence reading, and a share link. The reference to the sibling list_calculators makes the slug provenance unmistakable.

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?

Explicitly routes the agent to list_calculators for the slug and states what happens when inputs are omitted (example values are used). It does not name a when-not-to-use case or an alternative execution path, but with only two other siblings there is no real competing tool to disambiguate.

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