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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false, so the safety profile is covered. The description goes beyond them with cost (5,000 credits, Tier 7), a budget proportion warning, and an explicit confirmation requirement -- meaningful operational context. It does not resolve the title's 'PDF or HTML' ambiguity or state whether output is a link, upload, or inline bytes.

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 payload sentence is dense but front-loaded and every clause names real content in the report. The cost block is a separate bracketed line, which keeps the primary statement readable. No filler sentences.

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, and the description usefully previews report contents plus the premium cost gate. What is missing is only the PDF-vs-HTML selection question implied by the title and any routing against the narrative sibling; for a paid report renderer the description is otherwise complete enough to invoke.

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 67%, in the middle band, and the schema itself carries very rich per-field documentation (timezone, houseSystem, city-as-label-only). The description contributes no parameter meaning at all -- chart1/chart2, language, whitelabel, precision and fields go unmentioned. Baseline 3 is appropriate when the schema does the heavy lifting.

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 (Render) and resource (relationship synastry PDF) and enumerates the document's contents: Big Three, cross-chart aspect table, element/modality balance. It never names the closest sibling, astroway_reports_ai_synastry_narrative, so an agent cannot tell from the text alone which synastry output to choose.

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 cost block gives one precondition ('Confirm with user before invoking'), which is real invocation guidance, but there is no when-to-use / when-not guidance and no routing to alternatives such as the AI narrative or astroway_reports_generate. Usage is implied by the premium warning rather than explained.

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