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

Annotations only cover the read-only/idempotent profile, yet the description adds several things they cannot: Placidus is undefined beyond the polar circles and yields 422 houses_undefined_at_latitude, the cost is 0.1 credit per call billed per started block of 10 with only successful calls charged, sandbox keys are free, and results are deterministic. This is exactly the extra context the description should carry.

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 purpose, then the failure mode, cost, determinism and an example; each sentence carries distinct information. Slightly list-like, but nothing is padding.

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 an output schema present, return-value description is unnecessary, and the description still covers the one edge case (polar latitude with Placidus), the billing model, and determinism. Nothing material for correct invocation is missing.

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 100% and the enum values, defaults and lat/long conventions are all documented in the schema, so the baseline is 3. The worked example arguments add a small amount of invocation value but no meaning beyond the schema.

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 the resource precisely: ascendant, midheaven and twelve house cusps for a moment and place, which tells an agent exactly what comes back. It does not, however, differentiate itself from nearby siblings such as get_ephemeris_positions or get_chart.

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?

No statement of when to choose this over get_ephemeris_positions (planetary positions) or get_chart, despite twelve sibling tools. The reader must infer applicability from the returned data alone; there is no when-not guidance either.

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