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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=true and idempotentHint=false, so the safety profile is covered. The description adds one genuinely useful piece of behavioral context the annotations lack: the cost of 100 credits at Tier 4. It says nothing about latency, rate limits, or why repeated calls are not idempotent.

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 single sentence that enumerates the deliverable, followed by compact structured metadata lines for group, endpoint and cost. Nothing is padded, though the content list is a phrase fragment rather than a full sentence.

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 present, the description need not explain return values, and it covers purpose plus cost. The remaining gap is routing context — an agent has no stated reason to pick this over comparison_coach or the composite/davison path referenced in 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 description coverage is 100% and the chart objects carry very detailed field documentation (timezone, houseSystem, ayanamsa), so the schema does the heavy lifting. The description only implies the two-chart input via 'between two charts' and adds no format or constraint detail beyond the schema. Baseline 3 applies.

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 and resource ('AI interpretation of synastry between two charts') and enumerates the substance of the output: relationship dynamics, attractions, friction points, long-term outlook. It is distinguishable from the natal/transits/element siblings by the 'two charts' scope, though it never addresses how it differs from astroway_mcp_ai_comparison_coach or the composite/davison calculations the schema mentions.

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 no when-to-use guidance, no conditions or prerequisites, and no routing to alternatives such as astroway_ai_interpret_natal (single chart) or astroway_mcp_ai_comparison_coach. The bracket metadata names the group and endpoint but does not tell the agent when this tool is the right choice.

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