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

Annotations already declare readOnly=true, destructive=false, openWorld=true and idempotent=false; the description reinforces the read-only nature ("Reads or computes only and changes nothing"). More importantly it adds cost behavior the annotations cannot convey: $0.01/call, first 25 free, failed calls free, and that repeats are charged — which explains the non-idempotent hint in practical terms. No latency or rate-limit detail, but the billing disclosure is substantive.

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-loaded with the returned fields and coverage, then usage, then pricing — a sensible order. It is dense and somewhat run-on (the coverage sentence packs four asset classes), but every clause carries information; nothing 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?

For a one-parameter tool with no output schema, the description does the work the schema cannot: it enumerates the returned fields, states asset-class coverage, gives an example call, and discloses the billing model. An agent has everything needed to decide to call it and how to interpret the result.

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 100% and the single parameter already documents accepted formats (AAPL, VOLV-B.ST, ^GSPC, BTC-USD) or a company name. The description's example (symbol=AAPL) and format list largely restate that, adding little new syntax or constraint detail.

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?

Opens with a specific verb and resource ("Stock price and quote for any ticker or company name") and enumerates the returned fields, so the agent knows exactly what it gets back. It also states asset coverage (US/world stocks, ETFs, indices, FX, crypto pairs). It does not name the obvious sibling (stock_history) or explain how it differs from btc_price for crypto pairs, so sibling differentiation is implicit rather than explicit.

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?

Gives concrete usage contexts: "price a stock in an agent, check a move, or value a portfolio line", plus a worked example (symbol=AAPL). There are no explicit exclusions or named alternatives, so an agent must infer on its own that stock_history or btc_price might be preferable in some cases.

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