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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false. The description still adds genuinely new context: no authentication is required, which the annotations do not express. 'Does not change the plan' largely restates destructiveHint=false, so the added value is real but partial.

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?

Three terse sentences, front-loaded with what is returned, then the access constraint, then the non-mutation note. Efficient overall, though the final sentence overlaps with annotation-declared behavior.

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 single optional parameter, read-only listing tool with no output schema, the description actually sketches the return content (the three plan tiers and monthly prices). That is close to complete; only alternative-routing guidance is absent.

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% and the single currency parameter is fully documented there (GBP/EUR/USD/ILS, default EUR). The description adds no currency syntax or defaulting behavior beyond the schema, so the baseline of 3 applies.

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 concrete verb and resource (returns list prices) and names the exact data set (Free, Pro, Business monthly prices). This cleanly separates it from rate/quote siblings like get_data_rate or quote_call, which return different pricing concepts.

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?

It supplies a useful precondition ('No sign-in') and a negative scope note ('Does not change the plan'), which imply a safe informational lookup. However, it never states when to prefer this over related pricing tools (quote_call, get_did_rate, get_data_rate), so usage is only implied.

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