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

Beyond the readOnly/idempotent annotations, the description discloses that the call is free, reserves nothing, and starts nothing. This is important behavioral context for a pricing tool and is not redundant with the annotations.

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 short sentences each carry distinct value: what it returns, when to use it, and its side-effect profile. The key purpose is front-loaded.

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 quote tool with no output schema, it describes the returned values (cost, balance, plan eligibility), the applicable tools, and the safety profile. Parameter constraints are fully covered by the schema, and annotations cover side-effect safety.

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 schema already explains all five parameters. The description adds no parameter-level semantics beyond listing the same tool names in the enum.

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 specific function: returning the exact credit cost for a specified generation call before execution, plus balance and plan eligibility. Naming generate_image, edit_image, and generate_video as the priced operations differentiates it from the sibling generation and balance 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?

It explicitly tells the agent to use this tool whenever price or budget comes up rather than estimating. It does not, however, name alternative tools or exclusion conditions, such as when to use get_credits for balance-only queries.

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