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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so the safety profile is covered; the description adds genuinely new behavior: a ~two-week rolling refresh cycle that can lag the newest filing, and the guarantee that every response states its computation date. That staleness disclosure is exactly the kind of context annotations cannot carry. It stops short of describing response shape or error behavior beyond the schema's 'returns no data' note, so not a 5.

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?

Well structured and front-loaded: what it returns first, when to use second, when not to use third, freshness caveat last. Slightly long – the interpretability examples ('what growth rate is priced into a stock', 'value trap') are useful routing signal but push length; still, no sentence is filler.

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?

No output schema exists, and the description compensates by enumerating the returned fields and the freshness caveat, which is the main risk an agent needs to communicate. Combined with the exhaustive use/do-not-use routing against five siblings, nothing an agent needs to call this correctly is missing.

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?

Only one parameter and schema coverage is 100%, with the schema already documenting case insensitivity, BRK.B-style tickers, and the non-US/OTC exclusion. The description reinforces 'single US-listed company' but adds no syntax or format meaning beyond the schema. Baseline 3 is correct when the schema does the work.

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 and resource ('Returns Zyberno's stored valuation record for a single US-listed company') and then enumerates exactly which computed fields come back (Margin of Safety, Brina Gap, Brina Matrix quadrant, quality score, TTM fundamentals). It names the sibling tools it is not (screen_stocks, list_flagged_stocks), so an agent can route without opening any 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?

Explicit positive trigger ('when the user names a company or ticker'), an unusually valuable paraphrase list covering how users actually phrase valuation questions (priced-in growth, reverse DCF, value trap), and explicit exclusions with the correct alternatives for each (screen_stocks, list_flagged_stocks). It even states what this server does not hold at all: quotes, charts, news, ratings, earnings dates, non-US listings.

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