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

Annotations already declare the safe read-only, idempotent profile, so the bar is lower; the description goes beyond them by disclosing a concrete cost model ($0.10/call via x402 USDC, or prepaid credits via API key, 20 for $1.00). That pricing and auth requirement is exactly the kind of operational context an agent needs and is not captured in annotations.

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?

Purpose and workflow lead, with the long payment/auth clause relegated to the end where it does not block selection. The pricing sentence is information-dense rather than padded, though the second sentence is long and could be split.

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 9-parameter tool with deep nested objects and no output schema, the description sketches the kit's contents (beats, eye life, breath, voice line) and spells out payment, giving the agent enough to decide and prepare a call. It stops short of describing the returned structure in any concrete way, which is the main residual gap.

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 the schema already documents all nine parameters (shot enum, beats, nested state, target, eyeline, etc.). The description loosely echoes the components the kit is fitted to, which maps to shot/eyeline/target, but adds no syntax, defaults, or semantics beyond what the schema provides. 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 what the tool produces (a beat-by-beat 'direction kit' for a character state) and enumerates its components: behaviour fitted to shot size, eye life, breath, target-model rules, and a voice delivery line. It is specific about the resource, though the operative verb is implicit rather than front-loaded, and it does not distinguish itself from siblings like atlas_draft or atlas_journey.

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?

It provides a downstream workflow ('Write the acting prose from it, then atlas_lint the prose') and names atlas_lint, atlas_buy_pack and atlas_targets, which orients the agent. However, it never says when to pick this tool over the other creative siblings (atlas_draft, atlas_journey, atlas_show), so alternative selection 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.