feat(mcp): add readOnlyHint annotations so tools work in Cursor Ask mode (#1027)

All codegraph_* tools are query-only — they read the pre-built index and
never mutate the workspace — but they advertised no MCP annotations, so
Cursor's Ask mode (and any client that gates on read-only tools) blocked
every call with "you are in ask mode and cannot run non read-only tools."

Add a shared READ_ONLY_ANNOTATIONS constant (readOnlyHint: true,
destructiveHint: false, idempotentHint: true, openWorldHint: false) and
reference it from each of the 8 tool definitions. The field flows through
every tools/list path: the live getTools() (including explore's
spread-rewritten description), the static proxy getStaticTools(), and the
no-default withRequiredProjectPath schema clone.

The annotations field is additive, so it ships without bumping the
negotiated 2024-11-05 protocol version: clients that gate on it read it
regardless, and older clients ignore it.

Closes #1018

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -16,6 +16,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 - CodeGraph no longer times out when many agents query it at once. The shared background server that serves all your editor and agent sessions used to run every query on a single thread, so a burst of concurrent requests — for example a swarm of subagents exploring a large monorepo together — queued up behind one another and, while the heavy ones ran, froze the connection so finished answers couldn't even be sent back until the whole batch drained. Past a handful of simultaneous callers that routinely surfaced as MCP request timeouts. The shared server now answers queries across a pool of worker threads, so concurrent requests run in parallel and the connection stays responsive the whole time; when it's genuinely saturated a call returns a brief "busy, retry shortly" note (not an error) instead of hanging past your client's timeout. The pool sizes itself to your machine — roughly one worker per core, leaving one for coordination — and a single editor session is unaffected (no pool, no overhead). Set `CODEGRAPH_QUERY_POOL_SIZE` to choose a specific number of workers, or `0` to revert to single-threaded in-process queries.
 - Indexing now parses files across multiple CPU cores instead of one, so building a project's graph — `codegraph index`, the first index of a project, and the background re-index after changes — is faster on multi-core machines, most noticeably on large or parse-heavy codebases. The graph it produces is identical to before and re-indexing stays deterministic: parsing runs in parallel, but results are still committed in a fixed order, so the same project always yields the same graph. CodeGraph sizes the pool to your machine automatically (leaving a core free for everything else); set `CODEGRAPH_PARSE_WORKERS` to choose a specific number of parse workers, or `CODEGRAPH_PARSE_WORKERS=1` to restore the previous single-core behavior. Peak memory is unchanged — workers reclaim parser memory independently, so it doesn't grow with the number of cores. (#1015, #320)
 - When CodeGraph's MCP server runs with no default project of its own — started outside any repository (for example behind an MCP gateway), or at a monorepo root whose indexes live in sub-projects — it now marks `projectPath` as a required argument on every tool call. Before, `projectPath` was always optional, so an agent talking to such a server would often omit it, get back guidance to pass it, and not reliably retry — you had to nudge it by hand every time. Now the requirement is part of the tool definition the agent sees, so it supplies the path to the project it's working on the first time. When the server does have a default project — the normal case, launched inside your repo — `projectPath` stays optional and a call without it falls back to that project exactly as before. Thanks @wauxhall for the report. (#993)
+- CodeGraph's MCP tools now work in Cursor's **Ask mode** (and any other client that only permits read-only tools). Every CodeGraph tool just reads your indexed code — it never changes your workspace — but it didn't advertise that, so Cursor's Ask mode blocked every call with "you are in ask mode and cannot run non read-only tools," and you had to switch to Agent mode to use CodeGraph at all. CodeGraph now declares all its tools read-only using the standard MCP tool annotations, so Cursor (and similar clients) allow them in read-only contexts. Nothing about how the tools behave changes. Thanks @CDsouza315 for the report. (#1018)
 
 ### Fixes