Ephemeris Range

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

Annotations indicate readOnly, non-destructive, idempotent. The description adds constraints on step and range, plus optional filter, which are beyond annotations. Includes cost tier and group tag. No contradictions.

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?

Three brief lines plus a clear example, no redundant information. Purpose and constraints are front-loaded. Every sentence adds value.

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?

No output schema exists, so the description should hint at return format. It says 'Return planet positions' but does not describe the structure or fields. Given the tool's complexity (date range, step, planets), more detail on output would be beneficial. However, constraints and example partially compensate.

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?

With 0% schema coverage, the description adds meaning: 'configurable step (min 0.01 days)' explains stepDays, 'Optionally filter by planetIds' explains that parameter, and the example shows expected values. Only startDate and endDate are implicit but their format is in the schema pattern.

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 clearly states 'Return planet positions for a date range with configurable step', which is a specific verb+resource. The tool is distinct from siblings like 'planets' or 'horoscope_daily' which typically return single-date or interpreted data.

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 explicit constraints (step min, max range for sub-day vs. larger steps) and optional filtering, helping the agent decide valid inputs. However, it does not explicitly compare to alternatives like 'planets' for single-date queries.

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