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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is fully covered. The description adds the scope boundary (single stock, public data, not the user's portfolio), which is useful behavioral context, but says nothing about caching, data freshness, or failure modes for unknown tickers.

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 with no filler, and the usage trigger is front-loaded ahead of the exclusion. It is efficient and nothing is redundant, though the second sentence does the routing work that the first could have woven in.

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 an output schema present, the description does not need to describe return values, and the annotations carry the safety profile, so the scope note plus the enumerated outputs cover most of what an agent needs. The only real omission is any guidance on the ticker format, the one thing the schema leaves at 0% description coverage.

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 0% and the description never mentions the ticker parameter, its accepted formats (dotted classes, index carets, exchange suffixes), or case sensitivity, even though the schema's pattern allows 'BRK.B', '^GSPC' and 'NYSE:IBM' style values. The description therefore adds no meaning beyond the bare schema field name.

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 the specific resource (ValuEdge fair value for one stock) and enumerates the concrete outputs it returns: current price, margin of safety, valuation method, assumptions, confidence, and valuation risk. It also distinguishes itself from the portfolio siblings by stating it is not for a user's private portfolio, so an agent can route between it and get_my_portfolio without opening a schema.

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?

It gives an explicit trigger ('when the user asks for one stock's ... fair value') and an explicit exclusion ('Do not use it for a user's private portfolio'), which is more than most definitions offer. It stops short of naming the alternative tool to use instead (get_my_portfolio), so it is clear context rather than fully closed routing.

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