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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description's one real addition is the cost disclosure ('50 credits (Tier 3)'), which is useful billing context an agent cannot get from annotations or schema. It says nothing about output shape or error behavior, but the output schema covers returns.

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?

A single front-loaded sentence that carries the definition, followed by two short metadata tags. No filler, no restatement of the name, and the computational essence is stated first.

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?

Return values are covered by the output schema and safety by annotations, and the nested parameter objects are fully documented. The only substantive hole is family disambiguation — nothing tells the agent how this differs from composite or coalescent — but for a calculation tool with rich schema support the definition is otherwise sufficient.

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%, with the nested birth-data objects documented exhaustively (timezone vs timezoneOffset, houseSystem letters, rejected short forms). The description only echoes 'two birth moments', which maps to the required chart1/chart2 pair, and says nothing about the optional fields or precision parameters. Baseline 3 is correct when the schema does all the work.

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 ('Calculate a Davison relationship chart') and even explains the defining method — the midpoint in time and space between two birth moments. That is genuinely informative. However, it never names the sibling it must be distinguished from (astroway_relational_composite, which is the adjacent concept in the Comparisons family), so the agent must already know Davison theory to pick correctly.

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 only routing signal is the '[Group: Comparisons]' tag. There is no statement of when to prefer this over astroway_relational_composite, astroway_relational_coalescent, or astroway_relational_synastry, and no prerequisites or exclusions. For a family with four near-identical relationship-chart tools, that gap is significant.

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