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

Annotations already declare openWorldHint=true, idempotentHint=false, destructiveHint=false, so the safety profile is covered. For a streaming tool the critical undisclosed behavior is how the stream is delivered (polling, SSE, cadence, termination), which the description omits entirely. It does add the cost (10 credits, Tier 1) and time scope, which is genuine value beyond annotations.

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 description is extremely short and front-loads the scope ("Today + tomorrow sun events") before the structured cost/group tags. Nothing is wasted, though the brevity comes at the cost of substance rather than being lean-but-complete.

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. However, for a 5-parameter streaming tool, the description omits the single most important thing an agent needs — how the stream behaves and how to consume it — leaving it inadequate for the tool's complexity.

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 60%: fields, precision, and timezoneOffset are documented in the schema, while the two required parameters (latitude/longitude) are undocumented in both places. The description adds nothing about parameters, but latitude/longitude are self-evident by name, so the schema does most of the work.

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?

"Today + tomorrow sun events" names the resource (sun events) and a scope (today + tomorrow), but is a noun fragment with no verb — the streaming action is only implied by the title/name. It loosely distinguishes from siblings like stream_lunar_phase or stream_positions by resource, but never says it returns sunrise/sunset times specifically.

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?

No when-to-use guidance, no prerequisites, and no routing to alternatives such as astroway_webhooks_eclipse_alert or other stream_* tools. The "[Group: Real-time Streaming]" tag categorizes but does not tell an agent when to select this tool over its siblings.

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