Prediction Markets Quant

Base Rate Gap

base_rate_gap

Read-only

Use for "how does this price compare to history" and "is the market ignoring the base rate". Compares a market price with the historical base rate for a class of events: the gap in pp, a signal, and sample-size quality. Pass a known baseRateId (the parameter lists them) or your own baseRateValue.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "base_rate_gap"
  }
}

Input Schema

Name	Required	Description
`baseRateId`	No	Known base-rate id to look up (includes sample size + source).
`marketPrice`	No	Current market price in cents / implied probability % (0–100). Needed for a real answer. Accepts 55, "55%", "55¢", "$0.55", 0.55 or American odds (+120 / -150) — all read as 55%.
`baseRateValue`	No	Your own base rate in % (0–100), used when no baseRateId is given.

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedOct 23, 2026

removedInput schema / $schema

Removed value: -"https://json-schema.org/draft/2020-12/schema"

changedInput schema / properties / baseRateId / description

Previous value: -"Known base-rate id to look up (includes sample size + source). One of: incumbent_reelected · fed_hold_unemp_below_4 · fed_cut_cpi_above_3 · recession_called_12mo · sp500_positive_year · bitcoin_above_100k_eoy · gdp_growth_above_2 · cpi_above_3 · senate_incumbent_wins_primary · vix_below_20_eoy · interest_rate_cut_next_meeting · major_sports_upset."New value: +"Known base-rate id to look up (includes sample size + source)."

Changed2 schema fields changedOct 15, 2026
- removedInput schema / properties / marketPrice / anyOf
```
Removed value: -[
-  {
-    "type": "number"
-  },
-  {
-    "type": "string"
-  }
-]
```
- addedInput schema / properties / marketPrice / type
```
Added value: +[
+  "number",
+  "string"
+]
```

Changed4 schema fields changedOct 6, 2026

addedInput schema / properties / baseRateId / anyOf

Added value: +[
+  {
+    "type": "string"
+  },
+  {
+    "enum": [
+      "incumbent_reelected",
+      "fed_hold_unemp_below_4",
+      "fed_cut_cpi_above_3",
+      "recession_called_12mo",
+      "sp500_positive_year",
+      "bitcoin_above_100k_eoy",
+      "gdp_growth_above_2",
+      "cpi_above_3",
+      "senate_incumbent_wins_primary",
+      "vix_below_20_eoy",
+      "interest_rate_cut_next_meeting",
+      "major_sports_upset"
+    ],
+    "type": "string"
+  }
+]

changedInput schema / properties / baseRateId / description

Previous value: -"Known base-rate id to look up (includes sample size + source)."New value: +"Known base-rate id to look up (includes sample size + source). One of: incumbent_reelected · fed_hold_unemp_below_4 · fed_cut_cpi_above_3 · recession_called_12mo · sp500_positive_year · bitcoin_above_100k_eoy · gdp_growth_above_2 · cpi_above_3 · senate_incumbent_wins_primary · vix_below_20_eoy · interest_rate_cut_next_meeting · major_sports_upset."

removedInput schema / properties / baseRateId / enum

Removed value: -[
-  "incumbent_reelected",
-  "fed_hold_unemp_below_4",
-  "fed_cut_cpi_above_3",
-  "recession_called_12mo",
-  "sp500_positive_year",
-  "bitcoin_above_100k_eoy",
-  "gdp_growth_above_2",
-  "cpi_above_3",
-  "senate_incumbent_wins_primary",
-  "vix_below_20_eoy",
-  "interest_rate_cut_next_meeting",
-  "major_sports_upset"
-]

removedInput schema / properties / baseRateId / type
```
Removed value: -"string"
```

Changed2 schema fields changedSep 29, 2026

changedInput schema / properties / marketPrice / description

Previous value: -"Current market price in cents / implied probability % (0–100). Accepts 55, \"55%\", \"55¢\", \"$0.55\", 0.55 or American odds (+120 / -150) — all read as 55%."New value: +"Current market price in cents / implied probability % (0–100). Needed for a real answer. Accepts 55, \"55%\", \"55¢\", \"$0.55\", 0.55 or American odds (+120 / -150) — all read as 55%."

removedInput schema / required
```
Removed value: -[
-  "marketPrice"
-]
```

First observedSep 6, 2026

TDQS

A4.3/5.0

Behavior4/5

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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=false, so safety is covered; the description adds that marketPrice is "Needed for a real answer," signaling that omitting it degrades rather than fails the response. It also discloses the response surface (gap in pp, signal, sample-size quality), which annotations cannot convey. Minor gaps remain around error behavior when neither base-rate input form is supplied.

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

Conciseness4/5

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

Three tight sentences: purpose trigger first, then what it computes and returns, then how to supply inputs. Every sentence earns its place, though the nested quotation marks and the trailing input-hint sentence make the phrasing slightly denser than necessary.

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

Completeness4/5

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

With no output schema, the description carries the return-value burden and does describe the three returned elements (gap, signal, sample-size quality). Combined with the noted "needed for a real answer" cue on price and the id-vs-value fallback, an agent has enough to call it correctly, though the scale/meaning of the signal value is left unspecified.

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

Parameters4/5

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

Schema coverage is 100%, so the baseline is 3, but the description adds value by clarifying the selection logic between the two base-rate inputs: pass a known baseRateId (whose values the parameter enumerates) or your own baseRateValue. It also reinforces that marketPrice is what turns this into a meaningful answer, beyond the schema's format enumeration.

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

Purpose5/5

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

States a specific verb and resource — compares a market price against a historical base rate — and names the exact outputs (gap in pp, a signal, sample-size quality). The two quoted trigger questions plus the comparison framing make it easy to distinguish from siblings like calculate_ev, kelly_size, and market_pulse.

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

Usage Guidelines4/5

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

Explicitly states when to reach for it via the two quoted user questions ("how does this price compare to history", "is the market ignoring the base rate"), which is a clear usage context. It does not name when NOT to use it or which sibling to prefer for related calculations, so it stops short of a 5.

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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