Void session (refund)

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

With no annotations provided, the description carries the full burden and does so admirably: it discloses that real money moves back to the customer, that holds are released, that NovaPay returns no body, and that status must be checked separately. This is rich, accurate behavioral disclosure.

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?

The description is compact and information-dense. Three sentences cover purpose, usage guidance, behavioral caveats, and response handling—no wasted words, and the key action 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 simple one-parameter tool with no output schema, the description is complete: it explains the operation's effect, side effects (money movement), appropriate exclusions (unpaid sessions), and how to verify success (get_session_status). Nothing essential is missing.

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% and the only parameter, session_id, already has a clear description ('acquiring or checkout'). The tool description adds no further parameter-level detail, so the baseline score of 3 is appropriate.

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 uses a specific verb ('Cancel') and resource ('session'), clearly scopes to PAID or HELD sessions, and explicitly distinguishes itself from expire_session for unpaid sessions. This differentiates it well from sibling 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?

The description explicitly states when to use (paid/held sessions), when not to use (unpaid sessions → expire_session), and instructs to confirm with the user before use on paid sessions. It also advises checking the result with get_session_status, providing clear alternatives and follow-up steps.

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