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

readOnlyHint=true already tells the agent this is a safe read, so the bar is lower. The description adds real content beyond the annotation by stating the response combines schedules with currently-on-call users and by citing the underlying endpoint (GET /api/v2/on-calls). It still says nothing about pagination behaviour, token/permission requirements or result ordering.

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?

Three short sentences with the core resource and payload front-loaded; nothing is buried. The trailing API endpoint reference is marginally useful for mapping to the REST API but is the least load-bearing sentence.

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 no output schema, the description carries the burden of describing the return contents, and it does so at a high level (calendars plus on-call users). Pagination and token scoping live in the schema, and the read-only nature is covered by annotations, so the remaining gaps are minor for a zero-required-parameter list tool.

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% — page, per_page and the global-token caveat on team_name are all documented in the schema itself. The description adds no parameter-level detail, so the baseline 3 applies; it neither helps nor harms.

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 names a specific verb and resource ('List on-call calendars/schedules') plus the payload that matters ('the users currently on call for escalation'), which cleanly separates it from the incident, monitor, heartbeat and status-page siblings. The added 'who gets paged' gloss removes any ambiguity about what the listing contains.

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?

'Useful to see who gets paged' implies a use case but gives no when/when-not guidance, no mention of the team_name scoping option, and no alternative tool to pick instead. The agent must infer that this is the only on-call listing tool and that filtering requires a global token (which only appears in the schema).

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