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

Annotations only declare write/non-destructive/open-world, so the description carries the real behavioral load: idempotency ('overlapping ranges dedupe'), a size guardrail ('keep ranges to a few hundred points'), and a confirmation flow ('may return needs_confirmation'). This is meaningful context beyond the annotations, though it doesn't explain what is written or permission requirements.

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-loads the core action and the when-to-use cue early, and each clause carries operational information. The 'a chart with a year behind it is worth far more' line is motivational padding, 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?

For a 5-parameter mutation tool with no output schema and annotations covering only safety, the description is thorough: it explains idempotency, batching limits, series requirements, and the confirmation return. Only the meaning of approvalId and failure behavior remain unaddressed.

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 80%, so the schema already documents id, from, to, and workspace. The description adds the 'past range' framing and hints at confirmation (relevant to the undocumented approvalId), but provides no syntax or format detail beyond the schema. Baseline 3 is appropriate.

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 action (run the frozen instruction over a past range) and a clear outcome (give a metric history rather than starting today), which is distinct from ledger_feeds_run and ledger_feeds_preview. It doesn't explicitly name sibling tools, but the historical-vs-current framing makes the role legible.

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 an explicit trigger ('Offer this whenever you create a feed') and a meaningful precondition ('Works when the source returns a series; a source that only ever reports right now will write one point'). It lacks direct comparison to alternative feed tools, but the when-to-use guidance is clear.

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