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

Annotations already cover read-only, idempotent and non-destructive behavior, and the description still adds real context: 'Delayed' flags data latency, 'Google News, with source URLs' identifies the external source and provenance, and 'quoted as reported; no predictions' sets editorial expectations. That goes meaningfully beyond the structured hints.

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, front-loaded with what the tool returns and where the data comes from. The trailing 'no predictions' clause earns its place by preempting a likely agent misreading of the output.

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 and annotations covering the safety profile, the description only needs to frame purpose, source and scope, which it does. The one gap is the absence of usage guidance relative to alternatives, but for a two-parameter read tool this is minor.

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%, so the baseline is 3, but the description adds a constraint absent from the schema: crypto support is limited to 'top-250' assets. It also ties the asset/kind parameters to stock tickers vs crypto identifiers, giving useful scope beyond the schema text.

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 resource and content set: 'Delayed price and latest headlines ... for a stock ticker or a top-250 crypto asset.' An agent immediately knows it returns market data plus news, and it is clearly distinguishable from the fee/savings/platform siblings.

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 scope is stated ('stock ticker or a top-250 crypto asset'), which implies when it applies, but there is no explicit when-to-use/when-not guidance or reference to any alternative sibling. Usage must be inferred from the asset-scope phrase.

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