Rebillia MCP Server

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states this is a 'GET' operation, implying it's read-only and non-destructive, but doesn't confirm safety aspects like idempotency or lack of side effects. It also omits details like authentication requirements, rate limits, error handling, or response format, leaving significant gaps for a tool that retrieves data.

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 in the first sentence, followed by the API endpoint for technical reference. It avoids unnecessary words and stays focused, though the endpoint detail could be considered redundant if the agent already has structured API data. Overall, it's efficient but could be slightly more polished by integrating the endpoint info more seamlessly.

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 lack of annotations and output schema, the description is incomplete for a read operation. It doesn't explain what data is returned (e.g., rate plan details like name, price, or status), potential errors (e.g., invalid IDs), or how it fits into broader workflows (e.g., used before updates). For a tool with two required parameters and no structured output, more context is needed to guide effective use.

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 schema description coverage is 100%, with both parameters clearly documented as required IDs. The description adds no additional semantic context beyond what the schema provides, such as explaining what a 'rate plan' entails or how to obtain these IDs. Since the schema does the heavy lifting, the baseline score of 3 is appropriate, but the description doesn't compensate with extra insights.

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 ('Get a single rate plan') and resource ('on a subscription'), making the purpose immediately understandable. It distinguishes from siblings like 'list_subscription_rate_plans' by specifying retrieval of a single item rather than a list. However, it doesn't explicitly contrast with other 'get' tools like 'get_subscription' or 'get_subscription_rate_plan_charge', leaving some sibling differentiation incomplete.

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. It doesn't mention prerequisites (e.g., needing a subscription ID and rate plan ID), contrast with 'list_subscription_rate_plans' for multiple items, or specify use cases like retrieving details for updates or audits. Without this context, an agent must infer usage from the tool name and parameters alone.

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