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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false, openWorldHint=false), so the description is not required to restate that. It does add genuinely useful context the annotations cannot convey: the endpoint (POST /v1/symbolic-directions) and the cost (50 credits, Tier 3). It says nothing about input validation failures, precision behavior, or limits beyond cost.

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?

The core behavior and the key options are front-loaded in two tight sentences, followed by a clean metadata block for group, endpoint and cost. Every sentence earns its place and nothing is padded.

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 a rich nested input schema, an output schema, and full annotations, the description only needs to supply the domain semantics and cost, which it does. The one remaining gap is that it gives an agent no basis for choosing this tool over the neighbouring direction/progression tools.

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 carries the parameter burden and the baseline is 3. The description names the three `key` options and marks 'one_degree' as the default, which the schema's enum does not state, but it otherwise repeats the schema's own body description of the directional keys. Net addition is modest.

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+resource ('Calculate symbolic arc directions to natal points') plus the target scope, which is far more than the title alone. It does not, however, distinguish itself from the many proximate siblings (primary_directions, progressions, minor_progressions, tertiary_progressions), so an agent must infer the difference from the name.

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?

There is no when-to-use or when-not-to-use guidance, and no reference to any alternative tool. The only routing signal is the phrase 'for a target date', which is a weak implication rather than an instruction. With this many prognostics siblings, explicit differentiation is missing.

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