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

No annotations are supplied, so the description carries the full behavioral burden. It discloses scope and the mode/agency interaction, and 'currently active' implies a read-only live query, but it says nothing about ordering, freshness, authentication, rate limits, or what an alert record contains. Valuable but incomplete for a zero-annotation tool.

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?

One compact opening sentence states purpose and default, a second sentence covers the agency switch. Nothing is padded, and the key scope information is front-loaded before the filter details.

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 three optional params, no annotations, and no output schema, the definition covers everything an agent needs to construct a call: default agency, mode scope, and alternate agencies. The remaining gap is return-value shape and alert freshness, which is modest given the tool's simplicity.

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 enums documented for mode and agency, so the baseline is 3. The description adds only modest meaning beyond the schema – restating the TTC default and the agency=all behavior, plus new context that hsr stands for Hamilton HSR – without clarifying limit semantics or how mode interacts with agency=all.

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 opens with a specific verb+resource ('Get currently active service alerts') and scopes it to transit agencies and modes, so the agent knows exactly what the tool returns. It does not explicitly contrast itself with next_departures, route_vehicles, or search_stops, though their purposes are distinct enough that confusion is unlikely.

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 states the default agency (TTC), how to switch agencies ('Pass agency hsr... or agency all'), and a real usage caveat that 'the mode filter applies to TTC alerts only.' It stops short of saying when not to use the tool, but no sibling overlaps meaningfully with alert retrieval.

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