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

Annotations already declare the full safety profile (readOnly, idempotent, non-destructive, closed-world), and the description adds genuine context beyond them: cost (10 credits, Tier 1), endpoint (POST /v1/aspect-bar), and the semantic output behavior (bars span the orb duration, exact dates marked). It does not cover auth requirements or pagination/response-size limits for a date-range query.

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 transformation in the first sentence, followed by a compact metadata block for group, endpoint, required params, and cost. Efficient and scannable, with no redundant prose.

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. However, with 10 parameters at 20% schema coverage, six tuning parameters (maxOrb, stepDays, aspectAngles, the planet/visibility ID lists) are unexplained in both places, leaving the definition incomplete for correct invocation.

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 only 20%, so the description carries compensation duty, yet it explains nothing about maxOrb, stepDays, planet1Ids/planet2Ids, aspectAngles, or visiblePlanetIds — the parameters that actually shape the result. It confirms startDate/endDate as required, which the schema already states, adding little.

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 ('Transform aspect timelines into Gantt-style bars grouped by transit planet') and clarifies the output shape (duration in orb, exact dates marked). It clearly conveys this is a visualization/transformation tool rather than raw data, distinguishing it from data-returning siblings, though it never names astroway_aspects_aspect_timeline or astroway_render_timeline as relatives.

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?

'Useful for visual transit calendars' implies the intended use case but gives no explicit when-to-use, when-not, or alternatives. An agent must infer when to prefer this Gantt-bar form over the aspect timeline or render_timeline sibling.

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