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

Annotations already declare readOnlyHint=true, and the description reinforces the read-only behavior by describing what data is returned. It adds value by enumerating the returned fields (summary, description, reason, affected stops/routes, consequence, active time windows), which goes beyond the annotation's safety-only disclosure.

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 sentences, front-loaded with the purpose, followed by return contents and ID source. No filler; every sentence contributes useful information.

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 a single parameter and the readOnlyHint annotation, the description covers what the tool does, what it returns, and where the input originates. No critical information is missing for invoking it correctly.

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%, so the parameter is already documented. The description adds provenance ('Situation IDs appear in onebusaway_get_arrivals responses under situationIds and situations[].id'), which gives the agent guidance beyond the schema's type constraint.

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?

States 'Fetch full detail for a service alert (situation) by ID.' This is a specific verb+resource and clearly distinguishes from sibling tools like onebusaway_get_arrivals, which list alerts rather than fetch detail for a single ID.

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?

Explicitly tells the agent where to obtain the situationId (from onebusaway_get_arrivals under situationIds and situations[].id), which is the key usage prerequisite. It doesn't mention when not to use the tool, but the ID requirement makes the usage context clear.

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