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 that it returns both applying and separating aspects and that a call costs 50 credits (Tier 3), which is genuine extra context. It does not disclose anything about precision of aspect orbs, output size, or what inputs are mandatory beyond the 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?

Two short sentences with the core action front-loaded, followed by the return content, then bracketed group/endpoint/cost metadata. Zero filler, though the bracket lines are metadata rather than description and could be trimmed.

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 and the body schema is richly documented, so much of the burden is carried elsewhere. What remains missing is the routing information an agent needs among a dozen prognostics siblings and any note that full natal birth data plus a transit date are required. Adequate but with a clear gap at the decision level.

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 body schema is extensively documented, so the baseline is 3. The description adds nothing about the body, fields, or precision parameters; 'for a given date' gestures at transitDate but no syntax or constraint is added 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?

States a specific verb and resource: 'Calculate transit planet aspects to natal planets for a given date.' That is far more precise than a tautology. It stops short of differentiating from the sibling astroway_prognostics_transit_calendar, which an agent could easily confuse with this tool, so it is not a 5.

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 when-to-use or when-not-to-use guidance and no alternative is named, despite astroway_prognostics_transit_calendar and astroway_mcp_ai_explain_transit sitting in the same family. The only operational note is the cost line, which tells the agent the price but not when to choose this tool.

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