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

Beyond the safety annotations (readOnly/idempotent/non-destructive), the description discloses the exact cost (5,000 credits, Tier 7), that it consumes ~50% of the free monthly budget, and that the agent should confirm with the user before invoking. It also states the fallback behavior when `chart` is omitted. This is unusually rich behavioral context.

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 purpose, then the key usage rule, then grouped cost metadata. Every sentence earns its place with no redundancy; the metadata tags ([Group], [Cost]) are compact and scannable.

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?

An output schema exists so return values need not be described, and annotations cover the safety profile. The description adds purpose, the pivotal parameter rule, and cost/confirmation guidance — everything an agent needs to invoke 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 `chart` parameter has no schema description (anyOf with empty object), and the description is the only place its behavior is explained. `fields` and `precision` carry schema descriptions and `language` is a self-explanatory enum, so with 50% coverage the description fully compensates for the one ambiguous parameter.

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 verb and resource: 'Render a sample natal report PDF using the authenticated user's white-label configuration,' with scope implied by 'sample' and the white-label branding. This cleanly separates it from the general report generators (astroway_reports_natal, etc.), though it never explicitly names a sibling it is not.

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 gives concrete when-to-use context for the `chart` parameter ('Pass `chart` to use your own birth data; omit to use the bundled Kyiv 1990 sample') and a confirmation prerequisite for the premium cost. It stops short of naming an alternative tool or stating when not to use this one.

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