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

The description adds two behavioral facts the annotations do not carry: a 30-second tick cadence and a 10-credit (Tier 1) cost. However, with readOnlyHint=false and idempotentHint=false, the annotations leave open whether this opens a persistent stream, how it is terminated, or whether credits are charged per call or per tick, and the description does not resolve any of that; the word 'snapshot' also sits in mild tension with readOnlyHint=false.

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 compact and front-loaded: the purpose is the first clause, followed by the cadence and bracketed group/cost metadata. Nothing is wasted, though the bracketed tags are metadata rather than description prose.

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 described, and both parameters are covered. But for a streaming tool the description omits how the stream behaves, how long it runs, and how to stop it, and offers no routing against the many similar stream siblings, leaving real gaps for an agent deciding to invoke it.

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%, so both parameters (fields, precision) are fully documented with examples and defaults in the schema itself. The description adds nothing about parameters, and tickSeconds=30 is not one of the declared parameters, so this sits at the baseline of 3.

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 description names a specific resource and scope: 'Current planetary positions snapshot', which is concrete enough that an agent knows it retrieves a point-in-time set of planetary positions. It does not, however, differentiate itself from the many sibling stream_* tools (transit alerts, ingress, lunar phase), which is the main missing piece for 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 guidance and no mention of alternatives such as astroway_mcp_streaming, astroway_stream_transit_alerts, or the webhook subscribe tools. The only operational cue, tickSeconds=30, hints at a recurring cadence but does not explain when this snapshot is preferable to a one-off chart calculation or a subscription.

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