MCP Server

What's new — October 2026

The server now has 25 read-only tools, up from 17. Everything the site's browsers show, an AI assistant can now query too:

• list_all_star_years get_all_star_year Every All-Star season and roster, including the Negro Leagues East-West Game, matching the All-Star browser.
• list_negro_leagues get_negro_league get_negro_league_season The seven recognized leagues, their champions and clubs, and season standings with leaders, matching the Negro Leagues hub.
• get_this_day Birthdays, debuts, and final games on any date — the home page’s This Day in Baseball.
• list_managers Browse managers by career wins or name, matching the Managers browser.
• get_player_advanced_stats Season PA, BABIP, OPS vs. league, K/9, WHIP and more from the player page’s advanced tables.
• search_players now takes the Players browser’s position, era, and sort filters; list_franchises takes query and era; and get_player adds career OPS vs. league, All-Star selection years, and whether the player managed.
• Stricter arguments. A tool call with an argument the tool doesn’t declare now fails with a message naming the unknown argument and the supported ones, instead of quietly running on defaults. Invalid values come back with the specific problem, such as month and day must be passed together.

September 2026

The server just grew from 12 to 17 read-only tools, shipping alongside a wave of six new features across the site. Everything the new browsers show, an AI assistant can now query directly:

• search_parks get_park Every ballpark since 1871 — locations, former names, home-team tenures, and season-by-season attendance, matching the new Ballpark Browser.
• get_manager Full managerial careers with pennant and World Series flags, player-manager stints, and Manager of the Year awards, matching the new Managers Browser.
• get_player_postseason Postseason batting and pitching lines for any player, ordered the way a series run actually unfolded — wild card through World Series.
• get_player_fielding Season-by-season fielding plus career totals by position.

The same release brought the site the Negro Leagues hub (the seven recognized leagues, 1920–1948, with standings and leaders), the All-Star roster browser (including the East-West Game), and the daily This Day in Baseball widget — all built on the same data this server exposes. The baseball-history://server/workflow-guide resource routes the new question types, so connected assistants discover the expanded surface automatically.

How it works

The server exposes 25 read-only tools and 6 JSON resources over streamable HTTP. The hosted endpoint is https://baseball-history-mcp.azurewebsites.net/; point your MCP client at that URL and it is ready to use. If you prefer to run your own copy, start it with dotnet run --project baseball-history-mcp (or let the Aspire AppHost host it) and it listens at http://localhost:5190. Health endpoints are available at /healthz and /alive on either instance.

• The hosted instance is already connected to the database. A locally run copy requires a ConnectionStrings:Lahman value at startup; placeholder strings containing < are rejected.
• Every tool is read-only; the server never mutates data.
• Start with the get_server_diagnostics tool or the baseball-history://server/info resource to discover the surface before calling domain tools.

Connecting

Point your MCP client at the hosted endpoint https://baseball-history-mcp.azurewebsites.net/. There is nothing to install, no server process to start, and no connection string or API key to supply.

Claude Desktop / Claude Code

Add the server to your MCP configuration:

{
  "mcpServers": {
    "baseball-history": {
      "type": "http",
      "url": "https://baseball-history-mcp.azurewebsites.net/"
    }
  }
}

VS Code

Add a .vscode/mcp.json file:

{
  "servers": {
    "baseball-history": {
      "type": "http",
      "url": "https://baseball-history-mcp.azurewebsites.net/"
    }
  }
}

Running your own copy instead

To run the server locally, supply a database connection string through the ConnectionStrings__Lahman environment variable (the .NET double-underscore convention) or user-secrets, start the server, and swap http://localhost:5190/ into the url value above. The client never supplies the connection string.

ConnectionStrings__Lahman="Host=your-host;Database=baseball-history;Username=user;Password=secret" \
  dotnet run --project /path/to/baseball-history-mcp

Example prompts

Once connected, ask your AI assistant questions like these. It will choose and call the right tool:

Tools

Players

• search_players Search players by free-text query or last-name prefix, optionally filtered by position (P, C, 1B, 2B, 3B, SS, OF, DH) and era (a decade) and sorted by sort (name, hr, hits, games), with paging.
• get_player Get read-only detail for one player, including career batting, career pitching, team tenures, career OPS vs. league, All-Star selection years, and whether the player managed.
• get_player_advanced_stats Get season advanced batting (PA, ISO, BABIP, BB%, K%, OPS vs. league, HR/162) and pitching (IP, ERA, WHIP, K/9, BB/9) rates with qualification.

Franchises & Teams

• list_franchises List franchise summaries with optional league, name (query), and era filters and bounded paging.
• get_franchise Get one franchise with season-by-season history.
• get_team_season Get one exact team-season by team id, league, and year so franchise-era lookups stay deterministic.

Leaderboards

Hall of Fame

• list_hall_of_fame_inductees List inducted Hall of Fame rows with optional year/category filters and bounded paging.
• get_hall_of_fame_voting_history Get bounded Hall of Fame voting history for one player. Rows are Lahman HallOfFame ballot rows, not a prose biography.

Salaries

• get_player_salary_history Get bounded salary history for one player, ordered most recent to oldest.
• get_salary_leaders List highest salary rows with optional year filter and bounded paging.

Postseason & Fielding

• get_player_postseason Get bounded postseason batting and pitching lines for one player, ordered by year then round.
• get_player_fielding Get season fielding rows plus career-by-position totals for one player.

Ballparks

• search_parks Search ballparks by name, former name, or city; returns park keys for get_park.
• get_park Get one ballpark: location, former names, home-team tenures, and per-season attendance.

Managers

• list_managers List managers with career records, filtered by name and sorted by career wins or name; returns ids for get_manager.
• get_manager Get one manager's career: season records, pennant and World Series flags, and manager awards.

All-Star Games

• list_all_star_years List every All-Star season with game and selection counts and whether the East-West Game was played.
• get_all_star_year Get one season's games and rosters by league or squad, starters first, with Hall of Fame flags.

Negro Leagues

• list_negro_leagues List the seven Negro Leagues recognized as major leagues (1920–1948).
• get_negro_league Get one league's seasons with champions and its clubs' records.
• get_negro_league_season Get one league season's standings and top-five AVG, HR, ERA, and wins leaders.

This Day in Baseball

• get_this_day Get birthdays, debuts, and final games on a calendar day (date as MM-DD, or month + day), Hall of Famers first.

Diagnostics

• get_server_diagnostics Inspect safe runtime posture, configured limits, and connectivity without exposing secrets.

Resources

Read-only JSON documents the client can fetch to discover the server surface and usage guidance.

Calling the server from code

Use the official MCP client SDK to connect to the running server over HTTP and call tools directly. This C# example uses the ModelContextProtocol.Client package:

using ModelContextProtocol.Client;

var transport = new HttpClientTransport(new HttpClientTransportOptions
{
    Name = "baseball-history",
    Endpoint = new Uri("https://baseball-history-mcp.azurewebsites.net/")
});

await using var client = await McpClientFactory.CreateAsync(transport);

// Discover the available tools
foreach (var tool in await client.ListToolsAsync())
{
    Console.WriteLine($"{tool.Name}: {tool.Description}");
}

// Call a tool
var result = await client.CallToolAsync(
    "get_batting_leaders",
    new Dictionary<string, object?>
    {
        ["stat"] = "hr",
        ["fromYear"] = 2000,
        ["singleSeason"] = true,
        ["pageSize"] = 5
    });

Console.WriteLine(result.Content[0].Text);

The same connect → list → call flow is available from the official Python and TypeScript MCP SDKs.

Limits & data notes

• Page sizes are capped: player search 100, franchise list 50, Hall of Fame 50, batting/pitching leaderboards 100, salary leaderboard 50.
• Arguments are validated: names are case-sensitive and must match the tool’s input schema (for example playerId, not player_id), and an unknown name or out-of-range value returns a tool error (isError: true) explaining what to fix.
• History is bounded: Hall of Fame voting history returns up to 25 years; salary history up to 40 seasons.
• All data is from the Lahman Baseball Database; the server is read-only.
• Player IDs follow the Lahman convention (e.g. ruthba01, troutmi01); franchise IDs match Lahman codes (e.g. NYY); team-season lookups use team id, league, and year (e.g. NYA, AL, 1927).
• Salary data is available from 1985 onward. Innings pitched is stored as outs and converted to innings (outs / 3).