Routes

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

No annotations exist, so the description carries the full burden. It discloses the returned fields and the special overnight semantics, which is real context, but says nothing about result size, pagination, filter combination logic, or ordering for what is likely a large unfiltered list.

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?

Two compact sentences with no filler, and the enumeration of available data is front-loaded before the overnight special case. The parenthetical value lists make it dense but they earn their space given 0% schema coverage.

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 structure needn't be explained, and all three parameters receive semantic treatment. What remains missing is filter-interaction behavior and volume expectations for an unfiltered call, which matters for a catalog of this size.

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 0%, so the description must compensate — and it largely does, enumerating the accepted mode values (subway, lrt, streetcar, bus) and series values (rail, bus, express, blue-night, community, streetcar) and explaining overnight. The only gap is that it never states whether mode, series and overnight are AND-combined or independent.

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?

Opens with a specific verb+resource ("All TTC routes") and enumerates the attributes returned (mode, series, service hours by day type, overnight share), so an agent knows this is the route catalog. It does not name any sibling (route_stops, service_hours, find_stops) to draw the boundary, but the resource is distinct enough to be actionable.

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?

"overnight=true lists the Blue Night network" is the only conditional guidance and it is genuinely useful. There is no statement of when to reach for this tool versus service_hours or route_stops, and no mention of whether filters combine or what happens with no filters at all.

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