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

The annotations already declare readOnlyHint=true and idempotentHint=true, so the safety profile is covered. The description adds useful context by enumerating the exact payload fields, which matters because no output schema exists. It doesn't mention rate limits, error behavior, or delay/staleness of the tick, 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?

Two sentences with zero waste. The resource and payload are stated first, and the routing guidance follows, so it is properly front-loaded.

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?

This is a simple one-parameter read tool with annotations covering safety and no output schema, so the description's field enumeration fills the return-value gap. Everything an agent needs to select and call it correctly is present.

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 is documented there with format examples (AAPL, BRK-B, BTC-USD, EURUSD=X). The description only implies 'single ticker' scoping and adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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?

The description gives a specific verb and resource ('Spot price tick for a single ticker') and enumerates the returned fields (price, session change, % change, volume, timestamp), which lets an agent distinguish it from get_price_history and analyze_ticker without opening either 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?

It states the selection condition ('Use when only the current price tick is needed') and names two alternatives with the conditions that select them: historical OHLCV bars go to get_price_history and valuation multiples go to analyze_ticker. Nothing is left to inference.

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