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

Annotations already cover readOnly/idempotent/non-destructive, yet the description adds material beyond them: no credits are spent, no row is left in the request log, project Read is required, and the response shape (points capped at 200 with previews, batches with idempotency keys, credits, balance, fitsFirst) is spelled out. This is exactly the extra behavioral context that annotations cannot convey.

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 action, then details, then the no-write guarantees, with essentially no filler sentences. The single dense paragraph is information-rich but heavy, and the opening phrase ('data points past reads best') is slightly awkward, keeping it short of a 5.

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, so the description carries the return-value burden and does so explicitly (points, batches, credits, balance, fitsFirst). It also discloses the auth requirement and the non-mutating guarantee. Nothing needed to call this correctly is missing.

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 all four parameters are already documented in the schema, including the kind enum and the project slug. The description restates the detectable kinds and hints at the ordering/timeZone behavior but adds no syntax or format detail beyond the schema, so the baseline 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 specific verb+resource: cutting files into data points and pricing them as an estimate before anything is sent. It names the endpoint it mirrors (POST /api/v1/ingest/batch) and clearly separates itself from siblings like explain_ingestion or retry_ingestion. An agent knows this is a dry-run cost/point estimate, not an actual write.

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?

"before anything is sent" plus "Writes nothing, spends nothing" gives a clear condition for using it (preview/estimate prior to ingesting). It provides strong context but never names the alternative write tool to use once the estimate is accepted, so the when-not/when-to-ingest-anyway half is left to inference.

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