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

Beyond the readOnlyHint annotation, the description adds critical behavioral guarantees: nothing is executed, nothing is charged, and no key is required. It also discloses that the capability resolution is returned so interpretation is visible, which goes well beyond what the annotation alone provides.

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 sentences, each carrying distinct value: what it returns, the no-charge guarantee, and the no-key requirement. The most important framing is front-loaded, and there is no redundant or filler text.

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?

Given the tool has an output schema and annotations already covering read-only safety and open-world behavior, the description covers the remaining context: pricing without commitment, no authentication requirement, and comparison of alternatives. Nothing essential is missing for an agent to decide whether and how to invoke it.

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%, so the input schema already fully documents all three parameters. The description adds no parameter-specific meaning beyond what the schema provides, which aligns with the baseline of 3 for high schema coverage.

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 opens with a direct question that frames the tool's job, then enumerates exactly what is returned: resolved capability, eligible agents, actual price, and alternatives with cost/latency differences. It clearly situates the tool as a pre-commitment pricing step, distinguishing it from execution-focused siblings like execute_plan.

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 clear context for when to use it: before committing, when needing to know price, and even without an existing account or key. It stops short of explicitly naming sibling alternatives or stating 'use X instead', but 'Nothing is executed' strongly implies it is not for execution, and the title reinforces the before-committing trigger.

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