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

Annotations already declare readOnly, idempotent, non-open-world, non-destructive, so safety is covered; the description adds useful scope limits ('up to 150 tickers') and explicit non-capabilities ('does not recommend, predict or calculate tax') plus how failures are surfaced ('closest listings'). It does not discuss rate limits or latency, so it stops short of full disclosure.

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?

The core check and its output are front-loaded, and the boundary-plus-alternative sentence is efficient. The three quoted example questions take up noticeable space for modest routing value, costing a bit of tightness.

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?

Output schema exists, so return values don't need exhaustive description, yet the description summarizes them helpfully (validity, trading currency, closest listings). For a 2-parameter read-only tool with full schema coverage and annotations, this is nearly complete; only the 'base' currency behavior is left implicit.

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 both parameters are already documented (tickers with maxItems 150, base currency with default USD). The description repeats the 150 cap but does not mention the 'base' currency parameter or explain how it affects returned trading-currency figures. Baseline 3 applies when the schema carries the parameter burden.

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 uses a specific verb and resource ('checks tickers') and defines both input scope (up to 150 tickers) and output (usable price history, trading currency, closest listings for misses). It explicitly separates itself from search_symbols, so an agent can route between the two 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 gives the sequencing rule ('before a measurement'), sample user questions that map to the tool, and a named alternative with the exact condition that selects it ('when only a name is known, search_symbols'). It also states the negative boundary ('measures nothing'), which prevents misuse as a measurement tool.

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