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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), so the description's job is to add behavior it wouldn't otherwise know. It does: a cap of ten aspects, that each carries a short meaning, and that the reading is derived from the planets the chosen setting weighs. It does not say how missing birth times degrade precision (only the schema notes that), leaving a minor behavioral gap.

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 return value, then the input shape. No filler or restatement of the title. The second sentence is dense with three ideas (birth date, optional time, place) but every clause carries information.

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 structure need not be spelled out, and the 100%-covered nested person objects handle location and time-detail nuances. For a two-required-parameter computed-reading tool, the agent has everything needed to call it 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 coverage is 100%, so the baseline is 3; the description earns above that by explaining that the context setting is not merely a label but changes which planets are weighed in the reading - a semantic the schema's 'Relationship setting for the reading' does not convey. It also frames birth time as optional and a place as the locator, matching the schema's city/lat-long/timeZone alternatives without adding detail.

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: returns the tightest major aspects between two people's birth charts plus a reading for one relationship setting. That is far more precise than a generic compatibility tool. It stops just short of naming the sibling it differs from (check_sign_compatibility), so an agent must infer that this is the chart-based option and the other is the sign-based one.

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 purpose implies when to use it (two full birth charts, relationship reading), and 'one relationship setting' hints that context scopes the output. But there is no explicit when-to-use vs. when-not, and no mention of check_sign_compatibility as the lighter-weight alternative. Guidance is implied rather than stated.

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