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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description still earns credit for adding two facts not in the annotations: no authentication is required ('No sign-in') and no call is placed ('Does not dial'), which directly answers the side-effect question for a quote 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?

Two short sentences, front-loaded with what the tool returns and followed immediately by the two constraints that matter most (no sign-in, no dialling). Zero waste.

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 simple, read-only, no-output-schema quote tool this is nearly complete: the return intent and the two key behavioral constraints are stated. The remaining gap is that it never clarifies the country-vs-destination relationship or how it differs from check_call_rate.

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 50%: currency and destination are described in the schema, while country and number_type are undocumented in both places. The description hints that a number OR a country can be supplied (suggesting alternative inputs) but adds no format, enum, or mutual-exclusion detail beyond that baseline hint.

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 ('returns the rate-checker price') plus the two things that can be priced (a number or a country). However, it does not distinguish itself from the very similar sibling check_call_rate, nor from quote_number, which is a real ambiguity for an agent choosing among rate tools.

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?

'No sign-in. Does not dial.' implies this is a safe, non-authenticated pre-check operation, which is useful context. But there is no explicit when-to-use or when-to-use-an-alternative guidance, and the near-duplicate sibling check_call_rate is never addressed.

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