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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, and the description reinforces read-only behavior. It adds value beyond annotations by specifying the exact error for an unknown run_id (agent_run_not_found) and enumerating the returned fields, giving the agent a fuller picture of the call's behavior.

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 two sentences, front-loaded with the core action and returned fields, then usage guidance and error behavior. No redundant wording or filler.

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 compensates by listing the returned fields and the error condition. For a single-parameter, read-only tool, this is complete guidance for correct invocation and interpretation.

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% and the schema already explains run_id as the id returned by create_agent_run or list_agent_runs. The description adds no new parameter semantics beyond that, so the baseline score of 3 is appropriate.

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 fetches one persisted agent run by run_id and lists the exact fields returned (status, task, selected_tool, steps, result, tools_used, snapshot ids). It also names sibling tools that serve different purposes, making it easy to distinguish from list_agent_runs, get_agent_run_events, and get_agent_run_checkpoints.

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 explicitly says to use list_agent_runs to find run ids, get_agent_run_events for the event trail, and get_agent_run_checkpoints for replay checkpoints. This provides clear when-to-use guidance and routes the agent away from this tool for those needs.

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