ag_calc_stats

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

The description clearly indicates deterministic behavior and notes that the result includes a 'Guild-signed provenance envelope.' It also mentions being 'free for guests' with rate limits, implying a non-destructive read operation. While it doesn't explicitly state 'no side effects,' the pure calculation nature and the focus on a returned result provide adequate transparency.

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 somewhat repetitive: 'Deterministic' appears twice, and the payload schema is given inside the prose. It is structured in paragraphs but could be tightened. Still, the key information fits within a few sentences and is not excessively verbose.

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 calculation tool, the description covers input constraints, output format (including the embedded output schema), and the notable behavior of returning a signed envelope. It does not discuss error handling or edge cases, but given the deterministic and simple nature, an agent has sufficient context to call it correctly.

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?

The input schema only shows 'api_key' and a generic 'payload' object, but the description text embeds a detailed payload schema defining 'values' and 'percentiles' arrays, including constraints (up to 10k numbers, percentile range 0–100). The api_key is explained as enabling member budget. This compensates for the schema's lack of parameter descriptions, though the payload structure is not formally in the schema.

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 purpose: 'Deterministic descriptive statistics for a numeric series.' It enumerates the exact outputs (count/sum/min/max/mean/median/stdev/variance plus arbitrary percentiles) and differentiates from model estimation ('Exact arithmetic instead of model estimation'). The primary function is unmistakable.

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 gives no explicit guidance on when to use this tool versus alternatives. It mentions rate limiting and guest/member budgets, but these are access constraints, not usage criteria. There is no 'use when' or 'avoid when' statement, so an agent must infer applicability from the generic wording alone.

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