Screen the market

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

Annotations already cover read-only, idempotent, open-world and non-destructive behavior. The description adds real context beyond them: filters are conjunctive ("All given filters apply together") and index rows are excluded from results, both genuine behavioral facts an agent could not infer from structured fields.

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?

One dense, front-loaded sentence that opens with scope before listing use cases; nearly every clause maps to a real parameter, so little is wasted. It is long enough to read as a run-on, but the examples earn their space.

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 17 parameters, no required fields and no output schema, the definition covers the filtering half well but says nothing about what a result row contains or how limit/pagination behaves beyond the schema default. The "Egypt only" claim also leaves an agent unsure whether market=us/uae works, which is a real gap for a 17-param 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 coverage is only 47%, so the description must compensate, and it does explain several parameters through working examples (sortBy=changePercent, order=asc, minRelativeVolume=200, maxPeRatio, minDividendYield, index=EGX30, preset names, screenerId). However it incorrectly states "Egypt only" while the schema's market enum accepts us/uae/simulator, and it leaves limit, includeSuspended, min/maxPrice and min/maxChangePercent untouched, so the compensation is partial and partly misleading.

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?

Specific verb+resource: "filter and rank every instrument of the market using the live snapshot", with an explicit scope. It clearly distinguishes itself from siblings like get_market_movers (fixed movers lists), get_screeners (saved screener listing) and get_index_constituents, which it references rather than duplicates.

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?

Offers concrete when-to-use recipes (top gainers, top losers, most active, unusual volume, value stocks, sector, index members, preset, saved screener) and routes the agent to get_screeners and get_index_constituents for supporting ids. It never states when to prefer a sibling such as get_market_movers instead, so it stops short of full explicit alternatives.

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