Zipcar 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. While it mentions the filtering capability, it fails to disclose critical behavioral traits: it does not confirm this is a read-only operation (safe, non-destructive), does not describe the return format or structure of reservation data, and does not mention error conditions (e.g., if no reservations exist).

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 consists of two short sentences totaling 11 words. It is appropriately front-loaded with the primary action ('View past and upcoming Zipcar reservations') followed by secondary filtering details. The second sentence is slightly redundant with the schema's enum descriptions, but overall it is efficient with minimal waste.

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 has only two parameters with 100% schema coverage and no output schema, the description provides the minimum viable context for an AI agent to understand the tool's basic function. However, given the absence of annotations and output schema, the description should ideally disclose the read-only nature and general return value type to be 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 for both parameters ('filter' enum values and 'limit' purpose). The description mentions filtering by upcoming/past, which aligns with the schema but adds no additional semantic context, examples, or usage guidance beyond what the structured schema already provides. Baseline score applies.

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 tool 'View[s] past and upcoming Zipcar reservations,' providing a specific verb and resource. However, it does not explicitly differentiate this tool from sibling tools like 'reserve_car' or 'extend_reservation' (e.g., stating this is for viewing existing reservations rather than modifying them).

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 mentions filtering capabilities ('Can filter by upcoming or past reservations'), implying when different filter values might be used. However, it lacks explicit guidance on when to use this tool versus alternatives like 'search_cars' or 'get_car_details', and does not mention prerequisites such as authentication requirements.

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