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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint. The description adds that the tool returns alerts, advisories, detours, and suspensions, and explains route format. No contradictions. It doesn't mention pagination, but annotations suffice.

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 only two sentences, front-loaded with the purpose, then providing detailed usage examples. Every sentence is necessary and well-structured.

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?

With one optional parameter, no output schema, and comprehensive annotations, the description covers all necessary information. It explains the return type (alerts/advisories) and usage clearly. No gaps remain.

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 coverage is 100%, and the description adds significant value by providing examples (e.g., 'Paoli/Thorndale', '23', 'NHSL') and explaining the optional nature of the route parameter. This goes beyond the schema's brief 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 specifies the exact purpose: retrieving SEPTA service alerts, advisories, detours, and suspensions. It clearly distinguishes from sibling tools like 'septa_bus_positions' and 'septa_next_to_arrive' by focusing on alerts, not real-time positions or arrivals.

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 when to pass a route (to check one line) and when to omit (to list all active alerts). It provides concrete examples of valid route formats. While it doesn't explicitly state when not to use it versus siblings, the examples and context make usage clear.

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