ephemeris_progressed_chart

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is known. The description adds meaningful behavioral context beyond annotations: it explains the symbolic advancement (1 day = 1 year), lists return contents, and mentions credit cost. No contradiction exists.

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 well-structured: opening purpose sentence, a brief explanation of methods, credit notice, and a labeled example block. It is slightly longer than minimal but every sentence earns its place, especially the example which clarifies parameter usage.

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?

Given the tool's complexity (9 params, nested visual_config, no output schema), the description provides solid context: return contents (positions, cusps, aspects, retrograde), method variants, and a complete usage example. Some details are left to the schema, but the description is sufficient for an agent to understand the tool's role and typical call shape.

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 params are already fully documented. The description adds extra value by showing a realistic example with concrete values for birth_datetime, timezone, coordinates, and target_datetime, which helps correct usage. It also notes the credit cost structure for include_visual in the schema.

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 begins with a specific verb and resource: 'Calculate a Secondary Progressed (or Solar Arc / Tertiary) chart.' It clearly distinguishes this tool from sibling ephemeris tools like natal or transit charts by explicitly naming the progression methods and the returned data (planet positions, house cusps, aspects, retrograde status).

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 clear context on what the tool computes and even shows a concrete example with parameter values, making the intended usage evident. However, it does not explicitly state when to prefer this over sibling tools like ephemeris_transits or ephemeris_solar_return, so exclusions are not covered.

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