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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is fully covered by structured data. The description adds genuinely useful non-annotation context — the endpoint, the 10-credit Tier 1 cost, and the required inputs — but says nothing about latency, failure modes, or how the two charts are combined, and assumed return content is covered by the output schema.

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-line purpose sentence is front-loaded, followed by a compact bracketed metadata block (group, endpoint, required inputs, cost). Nothing is wasted, though the metadata block is machine-style scaffolding rather than prose, which slightly dilutes readability.

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-format explanation is rightly absent, and the annotations plus the 100%-covered input schema carry the heavy lifting. What remains missing is disambiguation within a very large sibling family of compatibility tools and any note on input assumptions (e.g. both parties need complete birth data for a meaningful score).

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 founder/partner nested birth-data objects and the fields/precision compact-mode parameters documented in detail in the schema itself. The description only repeats that founder and partner are required, adding no syntax or formatting meaning beyond what the schema supplies; 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?

'Founder × partner compatibility score' names a specific computed artifact and its two inputs, which is enough to separate it from generic sibling compatibility tools (astroway_relational_match_score, astroway_horoscope_compatibility, astroway_hd_human_design_compatibility). It is clear but does not explicitly state what makes it a *business/team* reading rather than a romantic one, so it stops short of full sibling differentiation.

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 states the required inputs and the credit cost but gives no when-to-use guidance, no prerequisites, and no pointer to the many alternative compatibility endpoints in the sibling list. An agent must infer the intended scenario from the tool name alone.

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