Crystal Code Web

A Crystal Code external tool set that gives the agent live web search and page fetch.

This is a native dotnet tool set for Crystal Code. websearch queries the hosted Parallel or Exa Search MCP endpoint and returns ranked, model-ready results; webfetch reads one HTTP or HTTPS page and converts it to text, Markdown, or raw HTML. The model chooses how much information comes back through numResults, contextMaxCharacters, and maxCharacters. The model-facing names match the Python web tool set.

Features · Tools · Configuration · Build from source

Features

• Search the live web. websearch calls the hosted Parallel Search MCP by default and Exa when the operator selects it. Parallel works anonymously.
• Model-controlled volume. numResults and contextMaxCharacters steer how much the Exa engine returns, and maxCharacters caps the returned text for either backend with a truncation note.
• Read specific pages. webfetch performs one HTTP GET, rejects non-text content, retries a Cloudflare challenge once, and converts HTML to plain text or Markdown.
• Stay bounded. Search responses are capped at 512 KiB and pages at 5 MiB. Search has a 25-second request timeout; webfetch honors its model-visible timeout. The host per-call timeout still applies.
• Keep credentials out of the wire format. The manifest and tool arguments never carry secrets. EXA_API_KEY and PARALLEL_API_KEY are read from the process environment and never written to output or logs.
• Fit the manifest. The set joins Plan and Work, declares approval: always, and loads websearch and webfetch from one assembly in one load context.

Tools

Tool	What it does
websearch	Search the live web through Parallel (default) or Exa and return ranked results as text
webfetch	Fetch one http(s) page as Markdown (default), plain text, or raw HTML

websearch arguments

Argument	Default	Meaning
query	Required	The web search query
numResults	8 (1–20)	Number of search results; the Exa backend honors it
contextMaxCharacters	10000 (1–50000)	Context size the search engine returns; the Exa backend honors it
type	auto	Exa effort: auto, fast, or deep
livecrawl	fallback	Exa live crawl: fallback or preferred
session_id	None	Stable conversation id reused across related Parallel calls
model_name	None	Exact model identifier for Parallel product analytics only
maxCharacters	None (1–100000)	Cap on the returned text; the tool truncates and notes it

webfetch arguments

Argument	Default	Meaning
url	Required	The http or https URL to fetch; credentials in the URL are rejected
format	markdown	Returned representation: text, markdown, or html
timeout	30 (1–120)	Request timeout in seconds
maxCharacters	None (1–100000)	Cap on the returned page text; the tool truncates and notes it

Configuration

Variable	Required	Purpose
CRYSTAL_WEBSEARCH_PROVIDER	No	Selects parallel (default) or exa
EXA_API_KEY	No	Exa credential; anonymous use works within free-tier limits
PARALLEL_API_KEY	No	Parallel credential; anonymous use works within free-tier limits
CRYSTAL_EXA_MCP_URL	No	Overrides the Exa endpoint; defaults to https://mcp.exa.ai/mcp
CRYSTAL_PARALLEL_MCP_URL	No	Overrides the Parallel endpoint; defaults to https://search.parallel.ai/mcp

Install

Publish the set and place the published files, including tools.json, in one directory under ~/.crystal/tools:

dotnet publish CrystalCode.Web/CrystalCode.Web.csproj -c Release -o ~/.crystal/tools/web

Restart the session, or run /tools reload, to load the set. A project set at <workspace>/.crystal/tools/web/ replaces the home set for that workspace. The directory name is the set identity; this set installs as web.

Build from source

You need the .NET 10 SDK and a sibling checkout of Crystal at ../Crystal. No CrystalCode checkout is needed at build time.

dotnet build CrystalCode.Web.sln
dotnet test CrystalCode.Web.sln
dotnet publish CrystalCode.Web/CrystalCode.Web.csproj

Crystal.Tools is referenced as a sibling source project. The production project adds no NuGet packages; the test project uses xUnit and Microsoft.NET.Test.Sdk only. WebSearchTool and WebFetchTool are public ITool types listed in tools.json; the host loads this class library in one isolated load context and wraps every call with its own approval, output truncation, and timeout.