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

Annotations already mark read-only, idempotent, non-destructive; description adds behavioral context by naming the source (SEC EDGAR fundamentals) and a specific limitation (no market price). It also explains why the limitation exists and offers a workaround, going beyond the annotation hints.

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?

Two tight sentences front-load the main content and then handle the key exception. No filler or redundant restatement of the schema.

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?

With one well-documented parameter and safety annotations, the description covers the essential return categories and the main limitation. The absence of an output schema is partly mitigated by enumerating returned figures, though a reader might want exact units or formatting.

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?

All parameter meaning is already in the schema (ticker with US stock example), so description doesn't need to add much. It reinforces the ticker context by framing the output as ratios for a ticker, but no new semantic detail beyond schema.

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?

Clearly identifies it computes financial ratios from SEC EDGAR fundamentals for a ticker and enumerates the categories (margins, returns, leverage, liquidity, per-share). Explicitly distinguishes itself by stating price-based ratios like P/E and P/B are absent, which separates it from a generic ratio tool.

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?

Implied usage is when you need fundamental ratios for a US ticker, and it explicitly warns price-based ratios are unavailable, directing users to divide by per-share figures. It does not name a sibling tool as an alternative, but the exclusion doubles as a when-not-to-use hint.

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