brief_result

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

With readOnlyHint=true, the annotation already covers the safety profile. The description adds some useful context—'one-line', 'agent-friendly', and avoiding a full JSON payload—but it does not go much beyond that. It also does not mention the optional caching side effect of as_handle, which is documented only in the schema.

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 compact and front-loaded. The first sentence states the core purpose, and the second adds the implementation detail plus the key usage scenario. No unnecessary repetition 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?

For selection and invocation, the description is sufficient: it names the required result_id concept, the one-line output, and the chaining use case. The rich schema covers the parameters and the output schema covers return shape. However, the description does not explain why data_path, data_columns, and data_sample_n appear on a tool that reads fitted results, which could confuse an agent.

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 parameter descriptions—especially detail with token estimates and as_handle with chaining behavior—are rich. The tool description itself adds little parameter-level meaning beyond framing result_id as a 'previously-fitted result', so the schema carries the weight.

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 a specific action and resource: 'Return the one-line agent-friendly brief for a fitted result.' It also signals the output format and context, and distinguishes itself from the broader 'brief' sibling by focusing on fitted results and agent-friendly summaries.

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 a clear use case: 'Useful when an agent wants to summarise a chained workflow without paying for the full JSON payload again.' This tells the agent when to call the tool, though it does not explicitly name alternative tools or state when not to use it.

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