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

Goes well beyond readOnlyHint/openWorldHint by disclosing the endpoint, per-call cost (0.005 credits), and the no-credential rate limit (25 calls/day per address) — exactly the operational facts an agent needs before invoking. Return fields (shares, USD value, % of portfolio, auto-classified delta) are also described.

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?

Front-loads the core behavior, then appends the return fields and operational details in a tight parenthetical. Dense but every clause carries information; the endpoint/credit/limit parenthetical is slightly cluttered but earns its place.

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 two simple parameters, no output schema, and a read-only annotation set, the description covers scope, default-quarter behavior, returned fields, cost, and credential-free limits. Nothing needed to call it 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?

With only 50% schema description coverage, the description compensates by explaining that quarter_end selects a specific historical quarter and that omitting it defaults to the latest available, matching the schema's stated default. The ticker parameter's format is left to the schema pattern.

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 ('returns every guru ... who held') and resource (curated 60-name roster holdings for a ticker), scoping to the latest 13F-HR quarter by default. This cleanly separates it from siblings like guru_portfolio, guru_moves, and smart_money_changes, which cover portfolios, moves, and quarter-over-quarter changes respectively.

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 per-ticker framing makes the use context obvious: fetch who among the curated gurus holds a given stock, optionally for a historical quarter. It does not explicitly name when to prefer a sibling (e.g., smart_money_changes for deltas across names), so it falls short of the explicit when/when-not/alternatives bar.

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