who_is_on_call

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

The annotations already declare readOnlyHint=true and openWorldHint=true, so the tool is known to be a safe read operation. The description adds the fact that it returns escalation tier information, which is useful context. However, it doesn't disclose return format, pagination, or any edge cases (e.g., behavior when no teams are specified). Given the annotations cover the safety profile, a score of 3 is appropriate—the description adds some value but not rich behavioral detail.

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?

The description is a single, efficient sentence with no filler words. It is front-loaded with the core question 'Who is on call' and immediately adds the per-team and escalation-tier scope. It earns a high score for conciseness, though it could be slightly expanded without losing efficiency.

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 and minimal annotations, the description carries the burden of explaining what the tool returns and how to call it. It fails to mention that team_ids and user_ids are optional filters, that timestamp defaults to now, or what the response structure looks like. An agent might mis-call the tool by providing required parameters that don't exist or missing optional ones. The tool is simple enough that a richer description could easily make it complete.

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 only 33% (timestamp has a description, team_ids and user_ids do not). The tool description does not explain the semantics of team_ids or user_ids, nor does it clarify that they are optional filters. Since the schema is under-documented and the description fails to compensate, the agent lacks critical information about how to use the filtering parameters.

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 clearly states the tool returns who is on call, per team, and includes escalation tier. It specifies the resource (on-call personnel) and the key output dimensions, which distinguishes it from sibling tools focused on operations or incidents. However, it doesn't explicitly mention filtering options or the ability to query by user, which could add further clarity.

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?

The description provides no guidance on when to use this tool versus alternatives, nor does it mention any exclusions or prerequisites. There is no statement like 'Use this to check on-call coverage' or 'For incident history, see list_incidents instead.' The agent is left to infer the tool's purpose from the name and description alone.

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