mbta_predictions

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

The description adds context beyond the readOnlyHint annotation by specifying that it returns arrival and departure times and covers specific transit modes. No behavioral surprises are disclosed, but the description is transparent about the tool's scope and output nature.

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 three concise sentences, front-loaded with the main action and resource. Every sentence provides essential information without redundancy, making it well-structured and easy to parse.

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?

The description sufficiently explains the tool's purpose and return values for a simple read-only query tool with optional parameters. It is complete enough given the schema coverage, though it could benefit from noting what happens when no filters are provided.

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 already documents all parameters with examples, achieving 100% coverage. The description only restates the filtering capability without adding significant new meaning beyond the schema, so a baseline score of 3 is appropriate.

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 provides real-time arrival/departure predictions for MBTA transit, using a specific verb 'Get' and a specific resource. It also distinguishes itself from sibling tools like mbta_vehicles and mbta_alerts by focusing on predictions.

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 explains how to filter by stop and/or route, giving clear usage context. It does not explicitly mention alternatives or exclusions, but the coverage of transit modes and the mention of filtering serve as sufficient guidance for a simple query tool.

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