Tools

All four tools are read-only, idempotent, and non-destructive; they reach Yahoo Finance’s public endpoints and nothing else. Every response carries retrieved_at, sources with provider timestamps, and caveats that name the limits of what was returned. Identical provider requests within 60 seconds are served from a short in-process cache; retrieved_at is still the time of the call.

Common parameter types:

• Query — text, 1–200 characters after trimming whitespace.
• Symbol — a Yahoo Finance symbol, 1–32 characters matching ^[A-Za-z0-9^=._-]+$ (for example AAPL, ^GSPC, BTC-USD, EURUSD=X, GC=F). Symbols are upper-cased.
• period — one of 1mo, 3mo, 6mo, 1y, 5y, ytd; default 3mo. Daily bars, or weekly bars for 5y.
• start / end — ISO dates (YYYY-MM-DD), both inclusive, always given together. They replace period with an exact window: end must be after start, not in the future, and at most 25 years later. Windows up to two years use daily bars, longer ones weekly. The response reports period as start..end.

search_markets — Search financial markets

Find ticker symbols and dated news links for a company, asset, sector, or market topic.

Parameter	Type	Constraints
query	Query	required
limit	integer	1–10, default 6; maximum symbols and headlines each

Response keys: query, retrieved_at, sources, instruments, news, caveats.

research_asset — Research an asset

One symbol with dated prices, period performance, risk statistics, price history, and related news links.

Parameter	Type	Constraints
symbol	Symbol	required
period	period	default 3mo; ignored when start and end are given
start, end	start / end	optional, both or neither

Response keys: symbol, period, interval, retrieved_at, sources, asset, latest_price, period_performance, statistics, price_history, news, partial_errors, caveats.

statistics holds observation_count, max_drawdown_percent (largest peak-to-trough decline in the returned series), annualized_volatility_percent (sample standard deviation of log returns, scaled by √252 for daily or √52 for weekly bars), and explanation. Both figures are null with an explanation when the series has fewer than three positive observations. They describe the returned series only; they are not forecasts.

A news failure is reported in partial_errors while prices are still returned; a chart failure is a tool error.

compare_assets — Compare assets

Compare 2–6 distinct symbols over aligned observation dates in their local currencies.

Parameter	Type	Constraints
symbols	list of Symbol	2–6 entries, duplicates removed
period	period	default 3mo; ignored when start and end are given
start, end	start / end	optional, both or neither

Response keys: symbols, period, interval, retrieved_at, assets, partial_errors, comparison, caveats.

Returns are computed only over session dates shared by every available asset. Symbols that fail are listed in partial_errors and marked available: false; mixed adjusted-close and raw-close bases are flagged as not comparable rather than blended.

market_overview — Market overview

Period returns for a fixed basket: ^GSPC, ^IXIC, ^DJI, ^RUT, ^VIX, ^TNX, DX-Y.NYB, GC=F, CL=F, BTC-USD, ETH-USD, EURUSD=X. The basket is chosen by Nomina; it is not a provider index.

Parameter	Type	Constraints
period	period	default 1mo

Response keys: period, interval, retrieved_at, assets, partial_errors, caveats. Each asset carries symbol, available, name, asset_type, currency, latest_price, period_performance, and source, or available: false with an error. The tool fails only when every basket member fails.

What it is not

• Unofficial public endpoints may be delayed, incomplete, unavailable, or rate limited.
• No real-time data guarantee; always use the provider’s quote and observation timestamps.
• Headlines and links only, not full articles or an exhaustive news search.
• No financial statements, analyst estimates, order execution, or account access.
• Adjusted closes are provider-defined; do not assume an audited total-return series.
• Returns exclude investor-specific fees, taxes and currency conversion.
• Short or unavailable histories and partial comparisons are explicitly identified.

Resource and prompt

• Resource nomina://sources (application/json) — provider, coverage, the limitations above, the privacy statement, and links to the privacy policy, this documentation, Yahoo’s privacy policy and terms of use.
• Prompt research_brief (topic: Query) — starts a concise, source-backed research brief that cites links and observation dates and separates facts from interpretation.