Polygon Io

Daily Open Close

daily_open_close

Read-onlyIdempotent

Fetch official open, high, low, close, volume, and after-hours/pre-market prices for a US stock ticker on a specific date (YYYY-MM-DD) from Massive (formerly Polygon.io).

Input Schema

Name	Required	Description	Default
`date`	Yes
`ticker`	Yes
`adjusted`	No

Output Schema

Name	Required	Description
`low`	No	Low price
`from`	No	Date of data
`high`	No	High price
`open`	No	Opening price
`close`	No	Closing price
`status`	No	API response status
`symbol`	No	Ticker symbol
`volume`	No	Trading volume
`preMarket`	No	Pre-market price
`afterHours`	No	After-hours price

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 8, 2026

changedInput schema / examples

Previous value: -[
-  {
-    "date": "2024-01-15",
-    "ticker": "AAPL"
-  },
-  {
-    "adjusted": true,
-    "date": "2024-01-15",
-    "ticker": "MSFT"
-  }
-]New value: +[
+  {
+    "date": "2026-09-25",
+    "ticker": "AAPL"
+  },
+  {
+    "adjusted": true,
+    "date": "2026-09-25",
+    "ticker": "MSFT"
+  }
+]

Changed2 schema fields changedMay 27, 2026

addedInput schema / examples

Added value: +[
+  {
+    "date": "2024-01-15",
+    "ticker": "AAPL"
+  },
+  {
+    "adjusted": true,
+    "date": "2024-01-15",
+    "ticker": "MSFT"
+  }
+]

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "afterHours": {
+      "description": "After-hours price",
+      "type": "number"
+    },
+    "close": {
+      "description": "Closing price",
+      "type": "number"
+    },
+    "from": {
+      "description": "Date of data",
+      "type": "string"
+    },
+    "high": {
+      "description": "High price",
+      "type": "number"
+    },
+    "low": {
+      "description": "Low price",
+      "type": "number"
+    },
+    "open": {
+      "description": "Opening price",
+      "type": "number"
+    },
+    "preMarket": {
+      "description": "Pre-market price",
+      "type": "number"
+    },
+    "status": {
+      "description": "API response status",
+      "type": "string"
+    },
+    "symbol": {
+      "description": "Ticker symbol",
+      "type": "string"
+    },
+    "volume": {
+      "description": "Trading volume",
+      "type": "number"
+    }
+  },
+  "type": "object"
+}

First observedMay 20, 2026

TDQS

A3.5/5.0

Behavior3/5

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is fully covered. The description adds useful context beyond that: the upstream source (Massive/Polygon.io), that data is 'official', and that gaps/pre-market fields are included. It says nothing about rate limits, auth, error behavior, or what happens on holidays.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

A single front-loaded sentence that packs verb, returned fields, scope, date format, and data source with no filler. Nothing is padded or repeated.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so return-value explanation is not strictly required (the field enumeration is a mild duplicate). The real gaps are the unexplained 'adjusted' parameter and no disclosure of behavior for missing dates, holidays, or adjusted-vs-unadjusted pricing, which matter for a 3-parameter, 0%-schema-coverage tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must carry parameter meaning. It does document the date format (YYYY-MM-DD) and the ticker domain ('US stock ticker'), but the third parameter, 'adjusted', is never mentioned, leaving that flag's semantics (split/dividend adjustment) entirely to guesswork.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb ('Fetch'), a specific resource (official OHLCV plus after-hours/pre-market prices), a scope (one US ticker on one date), and names the data provider. However it never names or contrasts the closest siblings (previous_close, grouped_daily, aggregates), so the agent must infer the boundary itself.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is only implied by the scope wording ('a specific date' for a single ticker), which weakly separates it from previous_close and grouped_daily. There is no explicit when-to-use/when-not or list of alternatives, and no note about non-trading days despite the market_holidays sibling.

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

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