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

With no annotations present, the description carries the burden. It reveals that the data is computed from VSOP87 ephemerides rather than table lookups, which is a useful behavioral nuance. However, it does not disclose any side effects, accuracy limits, or what the tool doesn't do (e.g., no houses, no aspects), leaving some behavioral context uncovered.

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 two concise sentences. The first sentence fronts the primary purpose and output, the second clarifies the computation method. No filler, no redundancy. It is efficiently structured with no wasted words.

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 simple read-only tool with three parameters, the description covers the essential context: what it returns, for a given moment, and how it computes. It lacks a detailed return format, but given the description of the output fields (sign, degree, retrograde) and no output schema, an agent can sufficiently infer the likely shape. The schema handles all parameter timezone details, and no additional prerequisites are evident.

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%: each parameter has a clear description in the input schema. The tool description adds nothing beyond 'given moment', which maps to the date/time expectations already defined. Therefore, a baseline of 3 is appropriate; the schema carries all burden.

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 function: it computes ecliptic longitudes of ten planets for a given moment, with specifics like sign, degree, and retrograde status. It is distinct from sibling tools because it focuses on planetary positions rather than moon state, aspects, or tarot. The computational method (VSOP87) is also noted, leaving no ambiguity about the deliverable.

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 explicit usage guidance is provided. The description does not say when to use this tool, when not to use it, or mention alternatives. The parenthetical 'rather than read from tables' references approach, not selection criteria, so an agent is left to infer from the name and siblings that it is for planetary positions.

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