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

Annotations already declare the safety profile (destructiveHint=false, openWorldHint=true, idempotentHint=false, readOnlyHint=false), so the description does not need to restate it. The description does add real context the annotations lack: the cost (10 credits, Tier 1) and the endpoint. It stops short of explaining what 'streaming' means here — one-shot list versus a live subscription — and never explains why a query-like tool is flagged non-read-only.

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?

The core sentence is front-loaded and free of padding, and the metadata block (group, endpoint, cost) is scannable rather than prose bloat. It loses a point only because the lead sentence is a verbless fragment rather than a complete statement of the operation.

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-value description is not required, and complexity is low with only 3 optional params. What is missing is the streaming semantics and the distinction from the webhook-based sign-ingress sibling — the two things an agent most needs to call this correctly instead of its twin.

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 coverage is 67%: 'fields' and 'precision' carry their own descriptions, but 'days' is undocumented in the schema. The phrase 'for N days' partially compensates by implying a forward window, though it gives no default, bounds, or unit guidance. Baseline 3 for a mid-coverage schema where the description closes only part of the gap.

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 fragment 'Next planet sign-ingresses for N days' names a specific resource (planet sign ingresses) and a scope (N-day forward window), which is enough for an agent to distinguish it from siblings like stream_positions or stream_lunar_phase. It does not, however, differentiate itself from the near-twin sibling astroway_webhooks_sign_ingress, and the verbless phrasing leaves the operation type implicit.

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 guidance, no conditions, and no named alternative. The agent is not told why it should pick this over astroway_webhooks_sign_ingress or astroway_stream_transit_alerts, nor what preconditions (if any) apply.

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