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

Annotations already declare readOnlyHint, openWorldHint, and destructiveHint, so the read-only nature is covered. The description adds valuable behavioral context: it clarifies that fcf/growth/discount/terminal/years are judgment calls (not looked up) and that passing a ticker triggers a price fetch. This goes beyond the annotations and explains side effects (lookup) without contradiction.

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 description is three sentences and front-loads the primary purpose, then explains input passing and the optional ticker. It is efficient with no wasted words, though it is slightly dense. It earns a 4 for structure and conciseness.

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?

Given the tool's complexity (7 params, 5 required) and lack of output schema, the description adequately covers the inputs and the optional price-lookup behavior. It does not explicitly state the return format, but the purpose implies it returns the intrinsic value per share, and the margin-of-safety mention hints at comparison. This is sufficient for an agent to call the tool correctly.

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 coverage is 100% with descriptions for each parameter, so the baseline is 3. The description adds semantic meaning by explaining that the five core parameters are user-supplied judgment calls and that ticker is used only to fetch the current price. It also implies the relationship between price and ticker (alternatives), which is not explicit in the schema but adds clarity.

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 states a specific action (compute a simplified DCF intrinsic value per share) with precise method (project FCF forward, discount back, add Gordon-growth terminal value). It clearly distinguishes this tool's scope from any generic calculator, and the lack of siblings makes differentiation non-issue.

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 description gives explicit guidance on when to supply the five judgment-call parameters directly and when to optionally pass a ticker to auto-fill the price. It does not mention alternatives or exclusions because there are no sibling tools, but it clearly instructs on parameter usage and the optional price-lookup path.

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