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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds the billing context (100 credits, Tier 4), which is genuinely useful for an agent deciding whether to call it, but says nothing about auth, rate limits, or period constraints.

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?

One front-loaded sentence plus two bracketed metadata tags; no filler, no restatement of the title. Every element earns its place.

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 annotations carry the safety profile. However, for a Tier-4 tool with an extremely close sibling, the definition omits the routing guidance an agent needs to choose correctly, leaving it only minimally complete.

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 the schema already documents body/fields/precision thoroughly. The description only says 'for a given period', which does not map cleanly onto the schema's required 'year' field, so it adds little beyond the structured data. 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?

States a specific verb ('Generate') and resource ('combined forecast calendar') and enumerates the content it produces: transits, lunar phases, ingresses, and retrograde stations. The word 'combined' hints at a superset of the sibling transit_calendar, but the definition never names or contrasts that sibling explicitly.

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 only scope hint is 'for a given period'. There is no when-to-use guidance, no statement of when to prefer this over astroway_prognostics_transit_calendar or astroway_prognostics_transits, and no prerequisites or exclusions. With a near-identical calendar sibling present, this is a real gap.

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