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

Annotations declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is already covered. The description adds valuable context beyond annotations: the report part is truncated to 20,000 characters with a one-hour signed URL. But it doesn't explain behavior for other parts (e.g., whether they are paginated or truncated), so it's not fully transparent.

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 dense sentences: the first front-loads the purpose and enumerates parts with special behavior, the second explains run_id origins and gives an example. Every clause earns its place with no waste.

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 read-only tool with full schema coverage and annotations covering safety, this description is nearly complete. It covers the key behavioral quirk (report truncation and signed URL), tells where run_id comes from, and gives an example. It could be slightly richer by clarifying behavior for non-report parts, but no output schema is needed.

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 coverage is 100%, so the schema already documents both parameters. The description repeats the part values and mentions the run_id sources, but doesn't add syntax or format details beyond what the schema provides. With full schema coverage, the baseline is 3.

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 states a specific verb ('Read') and resource ('one part of a finished run's result'), then enumerates the exact part values. This clearly distinguishes it from siblings like run_status (status, not result) and verification_result (verification, not the full run result). An agent can tell exactly what this tool returns without opening the schema.

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 tells the agent where run_id comes from (search_notes report hit, list_runs, start_run), which is essential context for when and how to invoke it. However, it doesn't explicitly state when NOT to use it or contrast it with alternatives like run_status or verification_result, leaving some routing to inference.

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