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

Annotations already declare the safety profile (readOnlyHint=false, idempotentHint=false, destructiveHint=false, openWorldHint=true). The description usefully adds the endpoint and a concrete cost of 10 credits (Tier 1), which annotations do not cover, but it says nothing about what 'stream' means in practice (one-shot snapshot vs. continuous/long-lived connection).

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?

Extremely terse and front-loaded: the output summary leads, followed by structured endpoint/group/cost metadata. No filler, though the body is almost too short to be self-sufficient.

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 explanation is not needed, and cost/endpoint are supplied. However, combining a streaming endpoint with readOnlyHint=false, the agent still lacks a clear statement of the connection's nature and duration, which is material for a stream tool.

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%: both 'fields' and 'precision' are fully documented in the schema, including format and defaults. The description adds no parameter meaning beyond that, so the baseline 3 applies.

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 resource (lunar phase) and states exactly what it yields: the current 8-phase plus a countdown to the next major phase. It is distinct from stream siblings like eclipse/ingress, but it never explicitly contrasts itself with them or with non-streaming alternatives.

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 call this versus other streaming endpoints (eclipse, ingress, void-of-course) or versus webhook subscriptions. The [Group: Real-time Streaming] tag implies a family but gives no selection criteria.

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