Struct ToolIndex 

pub struct ToolIndex {
    by_id: HashMap<String, McpTool>,
}

An in-memory index over all tools from all running MCP servers.

Build one via ToolIndex::from_tools, then use search and get_schema to serve progressive-disclosure meta-tool calls without exposing the full registry to external clients.

Fields

by_id: HashMap<String, McpTool>

Keyed by "<server_name>__<tool_name>".

Implementations

impl ToolIndex

pub fn from_tools(iter: impl IntoIterator<Item = (String, McpTool)>) -> Self

Build a ToolIndex from an iterator of (qualified_id, tool) pairs.

The caller is responsible for constructing qualified_id in the format "<server_name>__<tool_name>". See [build_tool_index] in gglib-proxy for the canonical construction path.

Duplicate IDs are silently overwritten by the last occurrence (mirrors the behaviour of the MCP server registry, which does not permit two servers with the same name to be active simultaneously).

pub fn search(&self, query: &str) -> Vec<ToolSummary>

Search the index by keyword and return at most SEARCH_RESULTS_CAP lightweight ToolSummary entries.

Matching

Both the tool_id and the tool’s description field are searched using case-insensitive substring matching. A tool is included if the lowercased query appears anywhere in either field.

An empty query returns the first SEARCH_RESULTS_CAP tools in an unspecified (but deterministic within a single process run) order — useful for an LLM that wants a broad overview before deciding what to fetch.

Hard cap

At most SEARCH_RESULTS_CAP results are returned regardless of how many tools match. This is intentional: searches that return too many results should be narrowed with a more specific keyword.

pub fn get_schema(&self, tool_id: &str) -> Option<&Value>

Retrieve the full JSON input schema for a single tool by its qualified tool_id.

Returns None when no tool with that ID exists in the index, or when the tool exists but its upstream server did not expose a schema.

Token cost

Calling this for a single tool is the central efficiency gain of the Progressive Disclosure pattern — the client pays only for the one schema it actually needs, not for all schemas in the registry.

pub fn contains(&self, tool_id: &str) -> bool

Returns true if the index contains a tool with the given tool_id.

Used by invoke_tool to validate the ID before attempting resolution against the live MCP service.

pub fn len(&self) -> usize

Total number of tools in the index across all MCP servers.

pub fn is_empty(&self) -> bool

Returns true if no tools are currently indexed (no MCP servers running or all servers have zero tools).

Trait Implementations

impl Debug for ToolIndex

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for ToolIndex

fn default() -> ToolIndex

Returns the “default value” for a type.