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

Annotations already declare readOnlyHint=false, idempotentHint=false and openWorldHint=true, so the mutation/regeneration profile is partly covered. The description adds material context the annotations do not: cost of 250 credits at Tier 5, the 'Heavy' flag, and the explicit instruction to confirm with the user first, which is exactly the kind of operational disclosure that matters.

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?

One front-loaded sentence gives the purpose, followed by a compact bracketed metadata block (group, endpoint, required, cost). No wasted prose, though the metadata is appended rather than integrated into the prose flow.

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 explained. Required parameters, cost, heavy-invocation warning, and endpoint are all present, giving an agent everything needed to decide and call 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 57%, and the description only enumerates chart1, chart2, language, tone, length by name without adding format, defaults, or semantic meaning. The nested chart-object details live entirely in the schema, so the description does not compensate for the coverage gap but the enumeration is a marginal help. 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 output (long-form relationship narrative) with its basis (cross-chart aspects), which distinguishes it from the natal/transit/monthly/year-ahead narrative siblings. It does not, however, explicitly contrast itself with the closely-related astroway_reports_synastry or astroway_ai_interpret_synastry tools, so the agent must infer the boundary.

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 'Heavy — confirm with user before invoking' warning plus the 250-credit cost is genuine usage guidance and the required params are listed. But there is no explicit when-to-use-vs-alternative routing (e.g. why this over astroway_ai_interpret_synastry), leaving the selection rationale implied.

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