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 adds genuinely useful context beyond them: a Premium API key is required and must be supplied as an 'Authorization: Bearer mt_live_...' header at connection time. It stops short of describing error behavior, quota consumption, or what 'the result' looks like.

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 action and outcome, followed by the auth requirement. Both sentences earn their place; no filler or repetition 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?

No output schema exists, so the description should carry the return contract; 'returns the result' is minimal but sufficient for a JSON-valued result. With read-only annotations, fully documented params, and an explicit auth prerequisite, the definition is close to complete, missing only error/quota behavior and the search-then-call workflow hint.

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%: slug and inputs are both documented in the schema, including the pointer that slug comes from search_calculators and that inputs maps every listed input name to a number. The description adds nothing beyond 'the given inputs', so the baseline 3 applies given the schema does the heavy lifting.

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 a MonsiTools calculator') plus the outcome ('returns the result'), so the agent can distinguish it from describe_calculator and search_calculators by action type. It does not explicitly name the siblings or route between them, but the purpose is unambiguous.

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 description gives no when-to-use guidance, no prerequisite chain (e.g., that the slug must first come from search_calculators), and no exclusions versus describe_calculator. Only an auth prerequisite is stated, which is not usage routing.

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