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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds the meaning of the directional keys (notably solar_arc being the progressed Sun's arc), which is useful context, but says nothing about permissions, credits being consumed at call time, or response shape.

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?

Two sentences, front-loaded with the core action and then the key options, with the group/cost metadata kept separate. Efficient, though the parenthetical about solar_arc could be tighter.

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?

With an output schema, full schema coverage, and rich annotations, the description does not need to explain return values. It is adequate for calling the tool correctly, but the absence of any routing guidance among the many prognostics siblings leaves a real gap.

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 coverage is 100%, so the baseline is 3, but the description goes further by explaining what each key value means and which is the default ('one_degree' default, 'solar_arc' = arc of progressed Sun), information the bare enum lacks. It adds no detail on fields/precision, which the schema already documents well.

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?

States a specific verb+resource ('Calculate symbolic arc directions to natal points for a target date'), which is clearly distinct from primary directions or progressions in the sibling list. It does not explicitly name or contrast those siblings, so an agent must infer the boundary itself.

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 when-to-use guidance relative to siblings like astroway_prognostics_primary_directions or astroway_prognostics_progressions, and no prerequisites stated. The only usage hint is the implied 'for a target date', which is minimal.

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