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

Annotations already declare this a safe, idempotent, non-destructive read. The description adds materially new behavior the annotations cannot convey: a 250-credit Tier 5 cost and an explicit requirement to confirm with the user before invoking. It stops short of describing runtime behavior such as computation time or failure modes.

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 tight sentences front-loaded with the technique and its output, followed by clearly delimited Group and Cost metadata. Nothing is padded, though the cost warning is slightly redundant with the tier label.

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 values need not be explained. For a 15-parameter technique-specific tool, though, the description leaves key gaps: what the required date/time/lat/long represent, and what a 'derived birth time' result looks like in relation to the input chart. Adequate to select the tool, thin for calling 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 description coverage is only 33% across 15 parameters, so the description must compensate and does not — it says nothing about date, time, latitude, longitude, or how timezone/ayanamsa/houseSystem affect a rectification result. It does not even clarify whether the required date/time is the recorded birth data being rectified or something else, which is the single most important semantic question here.

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?

Names a specific technique (Trutine of Hermes / Animodar) and the concrete outcome: deriving birth time from the prenatal syzygy Moon position. That is far more specific than the sibling astroway_prognostics_rectification, but the description never acknowledges that generic sibling or explains how the two differ, so an agent must infer the routing.

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 '⚠️ Heavy — confirm with user before invoking' note is genuine usage guidance about the invocation decision, and the cost tier frames it as expensive. However, there is no statement of when to choose this over astroway_prognostics_rectification or the other prognostics tools, nor what preconditions (known approximate birth data) are needed.

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