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

With no annotations, the description carries the behavioral burden, and it does so well: it explains the default planet set, accepted outer bodies, the difference between basic and full detail, and the exact per-planet return fields. It does not explicitly state side-effect-free behavior or error conditions, but the get/cached framing plus the detailed return specification make the behavior largely transparent.

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 organized into Args and return-value sections, each sentence adds useful information, and there is no filler. The key scoping phrase is front-loaded, and the parameter details are concise but complete.

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?

There is no output schema, so the description fills that gap by listing the per-planet return fields. It also covers defaults, optional inputs, and all detail-mode extensions. For a three-parameter read-style tool, nothing essential is missing for an agent to call it correctly.

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 0%, so the description must compensate, and it fully does. chart_id is tied to create_chart, planets lists examples and accepted bodies plus the default, and detail explains both allowed values and what 'full' adds. This is richer than the raw schema alone.

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 opens with a specific verb and resource: 'Get planetary positions for a cached chart.' It distinguishes itself from siblings like get_houses and get_aspects by specifying the resource type (planetary positions) and the precondition (a cached chart). The scope is unambiguous.

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 gives clear context: this tool operates on a chart_id produced by create_chart, and it is the tool to call for planetary positions. It does not explicitly name alternatives or state when not to use it, but the 'cached chart' precondition and the parameter documentation make the intended usage clear.

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