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

With annotations already covering read-only, idempotent, and closed-world behavior, the description adds useful context: deterministic JPL DE440 calculation, no LLM involvement, result SHA-256 hashing, pricing, and endpoint details. It does not describe the full return shape beyond the hash, but the safety and determinism profile is well communicated.

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 front-loaded with purpose and usage, then adds behavioral and pricing context. It is reasonably tight, though the REST endpoint and pricing sentence would not strictly be needed if the tool is already invocable through the MCP interface.

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 a 10-parameter tool with no required arguments and no output schema, the description covers the two main input modes, orb overridability, determinism, and result hashing. It omits detail on the exact returned aspect structure and default behavior when no input is supplied, but the rich schema reduces the burden on the description.

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 90%, so the schema already carries the parameter meaning. The description adds only marginal clarification—such as orbs being explicit and overridable and the longitudes {name: degrees} form—which mostly repeats what the schema already states.

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 states a specific resource—aspects—and specifies what they are computed for (a moment or supplied longitudes). It clearly distinguishes the tool's output focus from generic chart or transit tools, though it does not name any sibling tool explicitly.

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?

It gives two clear usage modes: provide a moment (datetime and optional place) to get aspects among planets, or provide longitudes for pure geometry. It does not state when not to use it or name alternative sibling tools, so it falls short of full routing guidance.

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