Composite Chart - Midpoint relationship chart with interpretations

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds useful behavioral context beyond that: it explains the midpoint calculation, the invariant that the Ascendant sits on the first cusp, and exactly what the response contains. No contradiction with annotations.

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 main action and method are front-loaded in the first sentence, and the body is reasonably tight. However, the trailing keyword string — 'Composite chart API, midpoint chart calculator, relationship astrology, couple chart analysis' — is redundant SEO filler that does not help an agent select or invoke the tool.

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?

For a read-only calculation with a full output schema, 100% parameter coverage, and helpful annotations, the description covers what the tool does, how it calculates, and what it returns. The only notable gap is the missing guidance on when to choose this over synastry, but that is a usage-guidance concern already scored separately.

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 the schema thoroughly documents all five parameters including person1/person2, lang, compact, and houseSystem. The description adds no parameter-level detail beyond referring to 'two natal charts,' which maps directly to person1/person2. 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?

The description opens with a specific verb and resource: 'Generate a composite chart by calculating midpoints between two natal charts.' It explains what the chart represents and the method used, which distinguishes it conceptually from relationship-comparison tools like synastry, though it does not explicitly name any sibling tool.

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 implies the tool is for relationship/couple analysis through phrases like 'relationship as a single entity' and 'couple chart analysis,' but it gives no explicit when-to-use guidance, no exclusions, and does not mention alternatives such as post_astrology_synastry. The usage context is clear only by inference.

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