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

Annotations already set readOnlyHint=true and idempotentHint=true. Description adds 'No payment required, no side effects' which reinforces safety. Also describes return values (amount_sats, breakdown, currency). No contradictions.

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 sentences, no filler. Front-loaded with purpose. Every sentence adds value: purpose, usage context, examples, return format, alternative 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?

Covers purpose, usage, examples, return fields, and behavior with/without params. No output schema but description mentions return structure. Could clarify that service must be a valid identifier from catalog, but that's minor.

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% with descriptions for each param. Description adds real usage examples (service=text-to-speech&chars=1500) and explains that omitting params lists all services. This goes beyond schema details.

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?

Description clearly states it provides an exact sat cost quote for a service before payment. Verb 'Get' and resource 'cost estimate' are specific. Distinguishes from sibling tools like create_payment, check_payment_status by focusing on pre-payment price checking.

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 says 'Useful for budget-aware agents to price-check before committing' which sets context. Provides example usage patterns (service=...). Does not explicitly state when not to use or alternatives, but context from sibling tools implies this is the estimation step.

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