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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered and the description's enumerated return fields add genuine value about what comes back. However, it says nothing about behavior for an unknown or malformed slug (error vs empty), which is the main behavioral question left open for a lookup tool.

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?

One sentence, zero waste, with the return payload front-loaded and the required input placed in its natural trailing slot.

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 no output schema, the description compensates well by enumerating the returned fields, and the read-only lookup shape is fully covered by annotations. The only material omission is failure behavior for a nonexistent slug.

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?

There is a single 'slug' parameter with 100% schema description coverage, including an example value, so the schema carries the parameter burden. The description's phrase 'given its slug' matches the schema rather than adding format or validation detail beyond it, which is the baseline case.

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 ('Returns') and resource ('a calculator's'), then enumerates exactly what is returned (name, category, formula, input names, page URL) and the key it is looked up by (slug). This clearly separates a metadata lookup from the sibling 'calculate' (which would compute) and 'search_calculators' (which would query), though it never names those alternatives explicitly.

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 'calculate' or 'search_calculators', and no preconditions or exclusions are given. An agent must infer from the verb 'Returns' that this is a lookup rather than a computation.

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