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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world behavior, so the safety profile is covered. The description adds the credit cost and that events are caller-supplied, but it does not disclose important behavior such as the default output format being json despite the SVG title, the 200-event cap, or the theme/css recolouring behavior; with annotations present, this partial coverage is a 3.

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?

Two front-loaded sentences state the output and the key input requirement, followed by compact group/cost metadata. There is no padding or repetition, though the brevity leaves the structured gaps to the schema.

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?

Given six top-level parameters, nested event objects, options with many fields, and only 33% schema description coverage, the description is not complete enough: it omits the output-format default, event structure, compact-mode fields/precision behavior, and option effects. The existence of an output schema removes the need to explain return values, but the input-side context is materially thin.

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 33%, and the description mentions only the events array, leaving rangeStart, rangeEnd, fields, options, and precision unexplained. It also adds no syntax or shape detail for event objects beyond the schema's required label/start/end, so it does not compensate for the low coverage.

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?

States a specific output: a Gantt-style horizontal timeline of transit/aspect events over a date window, and says the caller supplies the events array. It is clearly a rendering tool rather than data computation, but it does not name the sibling data tool astroway_aspects_aspect_timeline or otherwise distinguish itself from the many other astroway_render_* siblings.

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?

Provides only the input prerequisite that the caller supplies events; it gives no when-to-use guidance, no when-not-to-use guidance, and no alternative for obtaining the event data. The Visualization group label implies a rendering context but does not route the agent between this and astroway_aspects_aspect_timeline or other render tools.

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