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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds genuine context beyond that: it discloses that the content includes in-practice definitions and an explicit statement of what the service does and does not do — scope limits an agent cannot get from structured fields. It does not describe response size or format, keeping it short of a 5.

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 tight sentences with zero filler, front-loaded with the domain framing ('How sourcing works here') and ending on the actionable instruction. Every clause carries distinct information — mechanics, term definitions, and service scope.

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?

For a zero-parameter reference tool with annotations covering the safety profile and no output schema, the description gives enough to call it correctly and to know why to call it. Only minor gaps remain, such as whether the content is static or environment-specific and roughly what it returns.

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?

The tool takes zero parameters, so the baseline is 4 and there is nothing for the description to disambiguate. The description correctly implies a single no-argument fetch rather than suggesting any filtering or options.

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 makes clear this is a conceptual/reference tool that explains sourcing mechanics, capacity bands, fuel types, and the service's boundaries — clearly distinct in kind from search_buses or request_bus. It lacks an explicit 'this is not a search tool' contrast, so an agent must infer the differentiation from topic content rather than a stated negation.

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?

'Read this before telling a buyer what to expect' gives a concrete trigger condition and sequencing (read first, then advise). There is no explicit when-not-to-use clause or named alternative for cases where the agent actually needs bus listings, leaving one routing gap.

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