Katzilla MCP

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

Annotations already provide readOnlyHint=true, destructiveHint=false, idempotentHint=true, and openWorldHint=true. The description adds valuable context beyond this: it discloses the data source (Toronto TTC / UmoIQ), update frequency (daily), and details about the return format (Katzilla envelope with quality scores and citation info including SHA-256 hash). This enriches the agent's understanding of data provenance and reliability.

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 efficiently structured in two sentences: the first states the purpose and source, the second explains the return format and its components. Every sentence adds critical information without redundancy, and it's front-loaded with the core functionality.

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 moderate complexity (single parameter, read-only operation), rich annotations, and the presence of an output schema (implied by the description of the return format), the description is complete. It covers purpose, usage context, behavioral traits, and output structure, leaving no significant gaps for the agent to operate 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 one parameter (stopId) fully documented in the schema. The description adds marginal value by explaining that omitting stopId returns a route list, while including it triggers arrival predictions. However, it doesn't provide additional syntax or format details beyond what the schema already states, meeting the baseline for high schema coverage.

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's purpose with specific verbs ('Get Toronto Transit Commission (TTC) route list or real-time arrival predictions for a stop') and distinguishes it from siblings by specifying it's for TTC data only, unlike other transport tools like 'transport__bc-ferries' or 'transport__swiss-transport'. It explicitly mentions the resource (TTC routes/arrivals) and scope (Toronto).

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 clear context on when to use the tool (for TTC route lists or real-time arrival predictions) and implies usage based on parameter presence (omit stopId for route list, include for predictions). However, it doesn't explicitly state when not to use it or name alternatives among siblings, though the TTC focus naturally differentiates it from other transport tools.

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