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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds useful scope context — default is 'now', time is UTC, and the answer separates transit-only channels from person-completed ones — but says nothing about result size, uncertainty handling or failure modes.

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 sentences, front-loaded with the core output, no filler. The trailing clause 'apart from channels the transits form on their own' is slightly tangled but still earns its place by clarifying result structure.

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?

With no output schema, the description must convey what comes back, and it does: activated gates and lines, plus completed channels. Nested person input and uncertainty propagation are left entirely to the schema, which is acceptable at 75% coverage.

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 coverage is 75% with detailed per-field text, so the schema does most of the work. The description reinforces the UTC convention and the 'now by default' behaviour for date/time_utc, but adds no meaning beyond that for the nested person object.

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 verb and resource: what gates and lines the Sun, Moon, nodes and planets activate at a moment, plus the channels completed with a person's own gates. That second clause implicitly separates it from get_chart (which would give the person's own chart), though no sibling is named outright.

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?

Says defaults (now, or a given date/time in UTC) and hints at intent with 'the usual way to read a day's influence'. But it never states when to prefer get_chart or compare_charts instead, so the choice between siblings 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.