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 adds genuinely new operational context: the 50-credit Tier 3 cost, the HTTP endpoint, and the group. That cost disclosure is material for an agent deciding whether to call.

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 dense but front-loaded sentence gives the output and its inputs, followed by four short bracketed tags for group, endpoint, required params and cost. No filler, no repetition, easy to scan.

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, return values need no explanation, and annotations plus schema cover safety and parameters. The description supplies cost and scoring composition, but omits the sibling differentiation that would matter in a family this crowded with overlapping compatibility tools.

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 nested chart object is exhaustively documented in the schema itself. The description only restates that chart1 and chart2 are required and says nothing about the fields/precision compact-mode parameters, so it adds little beyond the schema.

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 states a specific output (a weighted 0–100 attraction score) and enumerates the exact contacts that feed it (Sun-Moon, Mars-Venus, ASC/DSC, etc.), which is far more informative than the title alone. It does not, however, distinguish itself from close siblings such as astroway_relational_match_score, astroway_horoscope_compatibility, or the near-identically named astroway_rel_synastry_attraction_score.

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?

There is no guidance on when to reach for this tool versus the many other relational/compatibility endpoints, nor any stated prerequisites beyond the [Required: chart1, chart2] tag. The agent is left to infer usage from the name and factor list.

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