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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful behavioral context beyond that: it enumerates the lifecycle states (queued through failed), lists returned fields including credits charged and any error, and frames the tool as a polling mechanism, though it omits details like behavior when the run id is invalid.

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 with zero waste: the first front-loads the core action and enumerates return contents efficiently; the second gives a terse, actionable polling instruction. Every element earns its place.

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 only one fully documented parameter, the description compensates by thoroughly enumerating the returned fields and lifecycle states. It also clarifies the polling usage pattern, making it complete enough for an agent to call the tool correctly without additional documentation.

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 input schema has 100% description coverage for its single parameter ('id': 'Run id'), so the schema already explains the parameter fully. The description reinforces that this is a run identifier by context but adds no syntax, format, or meaning beyond what the schema provides, making 3 the appropriate baseline.

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 uses a specific verb and resource ('Read one agent run') and enumerates exactly what is returned: state, summary, plan, model, tokens, credits, and error. It distinguishes itself from the sibling list_agent_runs by emphasizing 'one' run, and from run_agent by its read-only polling role.

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?

It explicitly states 'Poll this after run_agent', giving a clear primary use case. However, it does not mention alternatives like list_agent_runs for enumerating multiple runs or clarify whether it can be used outside the polling workflow, leaving a small gap in explicit when-not guidance.

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