Service Changes

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

With no annotations, the description carries the transparency burden and usefully discloses merged upstream sources, conditional ttc.ca publication, and best-effort reliability. It still omits explicit read-only status, authentication/rate-limit expectations, and failure/empty-result behavior beyond 'best effort'.

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 compact and front-loaded: source composition, filters, and reliability caveat appear in order. Every sentence contributes useful information without repetition.

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?

An output schema exists, so return-value documentation is not required here. The description covers sources, merge behavior, filters, and best-effort caveats, but it could be more complete by specifying parameter formats and how this tool relates to nearby alert/detour tools.

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 0%, so the description must explain both parameters. It does give meaning to both: route filtering and a date that the change must cover. It does not specify expected date or route formats, leaving some ambiguity.

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 identifies the resource and sources: board-period service changes built from GTFS-RT MODIFIED_SERVICE alerts and ttc.ca's service-changes list. It is specific about what the tool returns, but it does not explicitly distinguish itself from siblings such as alerts, detours, or service_status.

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?

It explains the available filters (route and date coverage) and notes that results are best effort, which implies usage for board-period route changes. However, it gives no explicit when-to-use/when-not guidance or alternatives versus alerts, detours, or service_status.

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