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

Annotations already declare readOnly, idempotent, non-destructive, and openWorld, so the safety profile is covered. The description adds 'Free' (cost) and characterizes the returned content, which is genuine extra context, but it omits rate limits, freshness/latency, and depth of coverage.

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 short sentences with the cost tag and the core question front-loaded, then the return content. No filler, though the phrasing is slightly informal ('what moved').

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, the description need not document return values, and it correctly focuses on what the tool answers and roughly what comes back. The only gap is a missing distinction from the numerous sibling market-summary tools.

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 coverage is 0% for the single 'limit' parameter, so the description should compensate. 'Returns the largest current company moves' loosely implies limit bounds the number of moves returned, but it never states the parameter's meaning or that it caps results at 10.

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 verb (answer/return) and resource (global market moves plus thematic news) with a clear temporal scope ('today'). It is distinguishable from siblings like global_snapshot or market_signal, though it never names or contrasts them explicitly.

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?

'Answer the concrete question: what moved in global markets today?' and the 'Free' tag imply the usage context (quick recap, cost-sensitive). There is no explicit when-to-use or when-not-to-use guidance relative to the many sibling brief/snapshot/signal tools.

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