Market data: pre/post-market prices

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

With no annotations, the description carries the full burden and does real work: it discloses two independent providers (Finviz after-hours print vs. TradingView derived from 1-minute Yahoo candles) and that the after-hours price and change are compared, warning the agent that sources may disagree. It omits freshness/delay characteristics and failure behavior when no extended-hours print exists, which keeps it below 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?

Front-loaded with the one-sentence purpose, then provenance, then Args/Returns. The docstring-style 'Args:' and 'Returns:' blocks partially restate the structured schema and output schema, which is mild waste, but the sizing is appropriate for the tool's complexity.

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?

The tool is simple (one parameter, output schema present), and the description covers purpose, data provenance, and the comparison behavior — enough to invoke it correctly. Gaps remain around data freshness and what is returned when no pre/post-market print exists, which matter for a dual-sourced price tool.

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% for the single required parameter, so the description must compensate; it does so only minimally by labeling it 'Ticker' and implying a US listing via the opening sentence. It adds no format, exchange, or symbol-resolution guidance beyond the bare schema.

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 scope: 'Dual-sourced pre-/post-market price for a US stock,' which is clearly distinguishable from regular-quote siblings like stock_quote or stock_prices. It never names those siblings explicitly, so an agent must infer the boundary rather than being told it.

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?

Usage is only implied by the resource name ('extended hours' → use when you need pre/post-market prints). There is no explicit 'use this instead of stock_quote when…' routing, no mention of when the data is unavailable (e.g. outside trading windows), and no stated prerequisites.

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