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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuine context beyond that: a bounded event sample rather than all stocks, returned headline links and actual numbers, and an explicit 'never trade recommendations' disclaimer. It stops short of describing sample size or latency.

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?

Three sentences with no filler, and the primary screening purpose is front-loaded. The second sentence ('Or find published analysis of exposure for other companies (read-through), separately from price evidence') is syntactically tangled and could be tightened, but it does carry a real mode.

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 9 parameters, an output schema present, and 89% schema coverage, the description covers the important extras: scope bound (event sample, not all stocks), output content (numbers and headline links), and mode distinctions. It does not clarify that all parameters are optional or what a default call returns, but the output schema carries the return-value burden.

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 89%, well above the 80% threshold, so the schema already documents hours, limit, query, screen, timestamps and min_initial_move_pct. The description only adds 'supports ticker, topic and dates', which is a generic restatement. The baseline 3 applies since the schema does the heavy lifting.

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 names a specific verb and resource ('find news where an initial price move reversed, faded... or continued') and enumerates the four screening modes, which maps directly to the screen enum. It implicitly separates itself from pure price tools and headline search, but it never names a sibling like explained_moves or search_headlines to make the boundary explicit.

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?

'Or find published analysis of exposure for other companies (read-through), separately from price evidence' hints that read_through is a distinct mode from price screening, which is useful routing. However, there is no explicit statement of when to pick this tool over siblings such as explained_moves or search_headlines, and no prerequisites or exclusions.

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