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 states the tool performs a GET operation, implying read-only behavior, but doesn't confirm if it's safe (non-destructive) or detail any authentication requirements, rate limits, error conditions, or response format. The HTTP method hint is useful but insufficient for a tool with zero annotation coverage.

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 concise and front-loaded, stating the core purpose in the first sentence. The second sentence provides the HTTP endpoint, which adds technical context without redundancy. Both sentences earn their place, though the endpoint detail could be considered slightly extraneous if the agent doesn't need HTTP-level information.

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 (retrieving a specific resource with two required IDs), lack of annotations, and no output schema, the description is incomplete. It doesn't explain what data is returned, potential errors, or behavioral constraints. For a read operation with no structured safety hints, more context is needed to guide the agent effectively.

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%, with both parameters clearly documented in the schema. The description adds no additional semantic context beyond what's in the schema (e.g., format examples, relationship between subscriptionId and chargeId). This meets the baseline score of 3, as the schema adequately describes the parameters without needing extra explanation in the description.

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') and resource ('a single rate plan charge on a subscription'), making the purpose understandable. It distinguishes from sibling tools like 'list_subscription_rate_plans' by specifying retrieval of a single charge. However, it doesn't explicitly differentiate from 'get_subscription_rate_plan' or 'get_subscription_upcoming_charges', which are closely related siblings.

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 charge ID), nor does it contrast with similar tools like 'get_subscription_rate_plan' or 'list_subscription_rate_plans'. The 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.