coin_historyHistorical price timeseries for a coin. (Current plan: up to 1825 days of history.)
| Name | Required | Description | Default |
|---|---|---|---|
| days | No | Days of history | |
| coinId | Yes | Canonical coin id (e.g. "bitcoin") |
| Name | Required | Description | Default |
|---|---|---|---|
| data | Yes |
Changes observed during successful MCP inspections.
Output schema / properties / dataAdded value: +{
+ "additionalProperties": true,
+ "properties": {
+ "coinId": {
+ "type": "string"
+ },
+ "days": {
+ "type": "integer"
+ },
+ "lastUpdated": {
+ "description": "ISO-8601 timestamp of the most recent refresh",
+ "type": "string"
+ },
+ "prices": {
+ "description": "Price points, oldest → newest",
+ "items": {
+ "additionalProperties": true,
+ "properties": {
+ "marketCap": {
+ "type": "number"
+ },
+ "price": {
+ "type": "number"
+ },
+ "timestamp": {
+ "description": "Unix epoch milliseconds",
+ "type": "number"
+ },
+ "volume": {
+ "type": "number"
+ }
+ },
+ "required": [
+ "timestamp",
+ "price"
+ ],
+ "type": "object"
+ },
+ "type": "array"
+ },
+ "source": {
+ "description": "Where the data came from",
+ "enum": [
+ "rate_history",
+ "cache",
+ "coingecko"
+ ],
+ "type": "string"
+ }
+ },
+ "required": [
+ "coinId",
+ "days",
+ "source",
+ "prices",
+ "lastUpdated"
+ ],
+ "type": "object"
+}Output schema / properties / pointsRemoved value: -{
- "description": "Price points, oldest → newest",
- "items": {
- "additionalProperties": true,
- "properties": {
- "timestamp": {
- "description": "ISO-8601 timestamp of the data point",
- "type": "string"
- },
- "value": {
- "description": "The recorded numeric value",
- "type": "number"
- }
- },
- "required": [
- "timestamp",
- "value"
- ],
- "type": "object"
- },
- "type": "array"
-}Output schema / properties / symbolRemoved value: -{
- "type": "string"
-}Output schema / requiredPrevious value: -[
- "symbol",
- "points"
-]New value: +[
+ "data"
+]Input schema / properties / coinIdAdded value: +{
+ "description": "Canonical coin id (e.g. \"bitcoin\")",
+ "type": "string"
+}Input schema / properties / symbolRemoved value: -{
- "description": "Coin symbol (e.g. \"btc\")",
- "type": "string"
-}Input schema / requiredPrevious value: -[
- "symbol"
-]New value: +[
+ "coinId"
+]Output schema / (root)Previous value: -nullNew value: +{
+ "additionalProperties": true,
+ "properties": {
+ "points": {
+ "description": "Price points, oldest → newest",
+ "items": {
+ "additionalProperties": true,
+ "properties": {
+ "timestamp": {
+ "description": "ISO-8601 timestamp of the data point",
+ "type": "string"
+ },
+ "value": {
+ "description": "The recorded numeric value",
+ "type": "number"
+ }
+ },
+ "required": [
+ "timestamp",
+ "value"
+ ],
+ "type": "object"
+ },
+ "type": "array"
+ },
+ "symbol": {
+ "type": "string"
+ }
+ },
+ "required": [
+ "symbol",
+ "points"
+ ],
+ "type": "object"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already indicate readOnly, idempotent, non-destructive. Description adds the limitation of up to 1825 days and hints at plan-dependency ('Current plan'), which is useful context beyond annotations.
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 concise sentences, front-loaded with the primary purpose. The parenthetical adds useful context without bloating.
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?
Given output schema exists (not shown), the description is minimally sufficient but lacks details on granularity (daily? hourly?) and data source, leaving gaps for an agent.
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 covers 100% of parameters with descriptions. The description adds no extra meaning beyond what the schema provides, meeting baseline but not exceeding.
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 clearly states it provides historical price timeseries for a coin, which is specific. It distinguishes sibling tools like get_price (current) and get_rate_history (rates) but doesn't explicitly contrast them.
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?
No guidance on when to use this tool versus alternatives like get_price or get_rate_history. The agent must infer from the description alone, with no explicit when or when-not advice.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.