Retrieve estimate

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

Beyond the readOnly/idempotent annotations, it discloses genuinely useful behavior: `estimate` is `null` until the first upload produces a run, `estimated_credits` is rounded up to the nearest 5, and the value is an estimate not a quote. This is rich, non-obvious context an agent needs to interpret results.

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?

Dense and front-loaded: purpose first, then workflow, then edge cases, all in a few tight sentences. The trailing 'Read operation.' is redundant with the readOnlyHint annotation and slightly dilutes the otherwise lean structure.

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?

There is no output schema, yet the description describes the returned shape (`estimate` nullability, `estimate.status`, `estimated_credits`) and the polling lifecycle, compensating for the missing output schema adequately for this read tool.

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%, so both parameters (source_id, account) are already documented in the schema. The description adds no parameter-level semantics beyond what structured fields provide, so the baseline of 3 applies.

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?

States a precise verb+resource ('latest credit estimate for a source') and scopes it to sources created with `require_approval`, distinguishing it from sibling tools like get_brain_source and approve_brain_source. An agent can identify its role 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?

Gives explicit workflow guidance: poll until `estimate.status` is `paused_for_approval`, then call the approve-source tool (named as a sibling workflow step). It tells the agent both when to call and what to do next, which is unusually actionable.

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