jpl_horizons

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

No annotations are provided, so the description carries full burden for behavioral disclosure. While 'ephemeris data' implies a read-only query operation, the description doesn't specify whether this requires authentication, has rate limits, returns real-time or historical data, or what happens with invalid inputs. For an 11-parameter tool with no annotation coverage, this is a significant gap in behavioral context.

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 description is extremely concise at just 6 words: 'JPL Horizons - Solar system objects ephemeris data'. Every word earns its place - it identifies the system (JPL Horizons), the domain (Solar system objects), and the function (ephemeris data). There's zero waste or redundancy, and the information is front-loaded effectively.

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?

For an 11-parameter tool with no annotations and no output schema, the description is inadequate. It doesn't explain what ephemeris data includes, what formats are returned, whether this is for observational planning or research, or how results are structured. The description should provide more context about this being a professional astronomy tool for precise positional calculations, not just 'ephemeris data'.

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 already documents all 11 parameters thoroughly with descriptions and enums where applicable. The description adds no additional parameter information beyond what's in the schema - it doesn't explain relationships between parameters (like how EPHEM_TYPE affects other parameters) or provide usage examples. Baseline 3 is appropriate when the schema does the heavy lifting.

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 the tool's purpose: 'JPL Horizons - Solar system objects ephemeris data'. It specifies the verb ('ephemeris data') and resource ('Solar system objects'), making it clear this tool retrieves positional/observational data for celestial bodies. However, it doesn't differentiate from siblings like 'jpl_sbdb' (Small-Body Database) or 'jpl_nhats' (Near-Earth Object hazard assessment), which may also involve solar system objects.

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?

The description provides no guidance on when to use this tool versus alternatives. With 22 sibling tools including other JPL tools (like 'jpl_sbdb' for small-body data) and NASA tools (like 'nasa_neo' for near-Earth objects), there's no indication of when this ephemeris-focused tool is appropriate versus those alternatives. The description doesn't mention any prerequisites, constraints, or typical use cases.

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