Rebillia MCP Server

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It effectively describes key behavioral traits: the tool performs a mutation (implied by 'Update'), has specific preconditions (only works on pending bill runs), and will fail on completed or error runs. However, it doesn't mention potential side effects, error handling details, or response format, leaving some gaps.

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 front-loaded with the core purpose, followed by essential details in a logical flow: required parameters, format specifications, and usage constraints. Every sentence earns its place by adding critical information without redundancy, making it highly efficient and well-structured.

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's complexity (mutation with preconditions), no annotations, and no output schema, the description does a good job covering key aspects: purpose, parameters, format, and usage constraints. However, it lacks information on the return value or error responses, which would be helpful for a mutation tool. It compensates well but isn't fully complete.

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?

The input schema has 100% description coverage, so the baseline is 3. The description adds value by reinforcing the required parameters ('Required: billRunId, newDateTime') and providing detailed format examples for newDateTime (ISO 8601 with timezone handling rules), which clarifies usage beyond the schema's basic descriptions. However, it doesn't explain the semantic meaning of billRunId beyond being an ID.

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 specific action ('Update a bill run') and resource ('bill run'), distinguishing it from sibling tools like 'get_bill_run' or 'list_bill_runs' by focusing on modification rather than retrieval. It provides explicit HTTP method context ('PUT /bill-run/{billRunId}'), which reinforces the update operation.

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 this tool ('only works on bill runs with status pending') and when not to use it ('Calls against completed or error runs will fail'), providing clear exclusion criteria. It also implicitly guides usage by specifying required parameters, though it doesn't name alternative tools for other statuses.

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