Rebillia MCP Server

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

With no annotations provided, the description carries full burden for behavioral disclosure. While it mentions the HTTP method (POST) and clarifies amount format, it doesn't address critical behavioral aspects: whether this requires specific permissions, if refunds are partial/full, whether the transaction must be in a refundable state, what happens to the original transaction, or what the response contains. For a financial mutation tool, this is a significant gap.

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 efficiently structured in three sentences: purpose statement, HTTP endpoint, and parameter details. It's appropriately sized for a 2-parameter tool, though the HTTP method detail could be considered implementation-specific rather than user-facing guidance.

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 financial mutation tool with no annotations and no output schema, the description is incomplete. It lacks information about behavioral constraints, response format, error conditions, and how this differs from related operations like voiding. The agent needs more context to use this tool correctly and safely in a payments system.

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 fully documents both parameters. The description adds minimal value by repeating the amount format example and noting both parameters are required, but doesn't provide additional context beyond what's in the schema. This meets the baseline expectation when schema coverage is complete.

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 clearly states the action ('Refund a transaction') and resource ('transaction'), making the purpose immediately understandable. However, it doesn't explicitly differentiate this tool from sibling tools like 'void_transaction' or 'get_transaction', which would be helpful for an agent selecting between refunding, voiding, or retrieving transaction information.

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 provides no guidance on when to use this tool versus alternatives like 'void_transaction' or other transaction-related tools. There's no mention of prerequisites, constraints, or typical use cases for refunding versus voiding, leaving the agent without contextual decision-making information.

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