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

The readOnlyHint annotation is already present, and the description adds useful context about the return content (all trips, stop sequences, departure times) and the default date. It doesn't contradict annotations and provides more than just the safety profile, though it doesn't disclose potential response size limits or failure modes. This is adequate given the 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 two sentences with no wasted words. The first sentence front-loads the core functionality, and the second gives the exclusion. Every part earns its place.

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 simplicity, the existing output schema, and the read-only annotation, the description covers everything an agent needs: what it returns, the default behavior, and the alternative for live data. No critical information is missing for correct usage.

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% — both routeId and date are well-described in the schema, including the default for date and guidance on finding route IDs. The tool description only restates the default behavior and doesn't add meaning beyond the schema, so the 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 states a specific verb and resource: 'Full-day schedule for a route' with details on what is included (all trips, stop sequences, departure times). It clearly differentiates itself from the live-predictions tool by naming onebusaway_get_arrivals, making it distinguishable among the many 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?

Explicit guidance is given: 'For live predictions, use onebusaway_get_arrivals at specific stops instead.' This tells the agent when not to use this tool and names the alternative. The default-date behavior is also mentioned, providing clear context for invocation.

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