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

Annotations already disclose openWorld/not-idempotent/not-read-only behavior, and the description adds value beyond them: the exact credit cost, the heavy/confirm-first warning, the output shape (narrative text plus model and token usage), and the ≤3200-token length cap. The grounding scope (Sun/Moon/Asc, 13 bodies, 12 houses, ≤25 aspects) is genuinely informative behavioral context.

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?

Front-loaded with the core purpose, then inputs, then return values, then a bracketed metadata block. Every line carries information (group, endpoint, required, cost). Slightly dense but no wasted prose.

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?

An output schema exists, so return values need not be fully enumerated, yet the description still notes them briefly. Required param, cost/tier, grounding detail, and token budget round out what an agent needs. The only shortfall is that fields/precision semantics are left entirely to the schema.

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 only 50%, so the description must compensate. It covers chart, language ('21 codes'), tone (warm/professional/concise) and length (short/medium/long; ≤3200 tokens), which is useful. However, it omits meaning for the compact-mode params fields and precision, which the schema carries, leaving a partial gap. Baseline 3 is appropriate.

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: 'Long-form natal-chart narrative (markdown)' grounded on a computed natal chart. This clearly separates it from the AI monthly/synastry/transit/year-ahead narrative siblings. It does not, however, explicitly contrast with astroway_reports_natal or astroway_ai_interpret_natal, so sibling differentiation is incomplete.

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 metadata block gives a crucial usage cue: 'Cost: 250 credits (Tier 5)' and 'Heavy — confirm with user before invoking.' That is real when-to-invoke guidance. But there is no explicit routing against alternatives (e.g., when to prefer the non-AI reports_natal or a shorter narrative variant), so usage is only implied.

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