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

Annotations only cover safety (readOnly, idempotent, non-destructive); the description goes well beyond them, disclosing that estimates use the draft graph (the same one run_pipeline executes), how `cheaper` and `preview` are derived, and the UI affordance (Start render button) that supplies the go-ahead.

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?

Front-loaded with the core purpose, and the later sentences earn their place because no output schema exists and the response fields must be explained. Some sentences are dense and long, but there is little redundancy.

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 explaining what the estimate returns (`lines`, `cheaper`, `preview`) and how the preview ties back to run_pipeline. Combined with the explicit workflow guidance, an agent has everything needed to call it and act on the result.

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 0%, but there is a single, self-describing parameter (pipelineId), and the description scopes it implicitly to 'a pipeline you built or changed in this conversation.' It adds no format or id-syntax detail, but nothing about the parameter is ambiguous.

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?

Specific verb+resource: it estimates the credit cost of one pipeline run and names the response fields (`lines`, `cheaper`, `preview`). It is clearly separable from run_pipeline, which it repeatedly references as the execution counterpart.

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?

Explicit when-to-use: 'Call this before running a pipeline you built or changed in this conversation,' with the required follow-through (tell the person the price, wait for go-ahead before run_pipeline). It also names the alternative (run_pipeline with preview: true) and the condition that selects it.

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