call-graph

name	call-graph
description	Navigate the call graph — callers, callees, call trees, entry points, dead and isolated symbols.
allowed-tools	["mcp__mycelium__get_callees","mcp__mycelium__get_callers","mcp__mycelium__get_callee_tree","mcp__mycelium__get_caller_tree","mcp__mycelium__get_entry_points","mcp__mycelium__get_dead_symbols","mcp__mycelium__get_isolated_symbols","mcp__mycelium__get_leaf_symbols","mcp__mycelium__find_call_path","mcp__mycelium__get_common_callers","mcp__mycelium__get_common_callees","mcp__mycelium__rank_symbols"]
category	analysis
icon	📞
marketplace_examples	[{"query":"Who calls the login function?","tool":"mcp__mycelium__get_callers"},{"query":"What does AuthService.login transitively call?","tool":"mcp__mycelium__get_callee_tree"},{"query":"What are the entry points of this project?","tool":"mcp__mycelium__get_entry_points"},{"query":"What functions are dead code?","tool":"mcp__mycelium__get_dead_symbols"},{"query":"Is there a call path from cli_main to verify_password?","tool":"mcp__mycelium__find_call_path"}]

call-graph — who calls who, and what stays in the dark

This Skill bundles the seven Calls edge-kind tools. Reach for it any time the user asks a "what calls X" or "who can reach Y" question, or wants reachability-based code-health diagnostics (dead code, entry points, isolated functions).

When to invoke this Skill

Use when:

• The user asks "who calls X", "what does X call", "is X reachable", "what dies if I delete X".
• The agent is planning a refactor and needs blast-radius information.
• The user wants code-health views: entry points, dead symbols, isolated nodes.

Do NOT use when:

• The relationship is Imports, Extends, Implements, etc. — use import-graph, inheritance (planned).
• The user wants a ranking of callees by importance — see centrality.
• The user wants multi-hop set reachability across edge kinds — see reachability (planned).

Quick examples

Developer question	Tool
"Who calls the login function?"	mcp__mycelium__get_callers
"What does AuthService.login transitively call?"	mcp__mycelium__get_callee_tree
"What are the entry points of this project?"	mcp__mycelium__get_entry_points
"What functions are dead code?"	mcp__mycelium__get_dead_symbols
"Is there a call path from cli_main to verify_password?"	mcp__mycelium__find_call_path

Capabilities under this umbrella

get_callees — direct callees of a symbol

mcp__mycelium__get_callees({ "path": "src/auth/session.rs>AuthService>login" })
→ { "callees": ["src/db.rs>users>find_by_email", "src/crypto.rs>verify_password", ...], "count": 5 }

edge_kind (v0.1.12, Issue #297) — query a specific edge kind instead of the default Calls. Accepted values: calls (default), imports, extends, implements.

mcp__mycelium__get_callees({ "path": "src/auth.rs>login", "edge_kind": "imports" })
→ { "callees": ["src/crypto.rs", "src/db.rs"], "count": 2 }

get_callers — direct callers of a symbol

mcp__mycelium__get_callers({ "path": "src/auth/session.rs>AuthService>login" })
→ { "callers": ["src/api/routes.rs>handle_login", "src/cli/main.rs>cli_login"], "count": 2 }

include_virtual (v0.1.11) — also include virtual/dynamic dispatch call sites (trait object calls, dyn Trait dispatch). Off by default because virtual edges are approximate.

mcp__mycelium__get_callers({ "path": "src/auth/session.rs>AuthService>login", "include_virtual": true })

edge_kind (v0.1.12, Issue #297) — query a specific edge kind instead of the default Calls. Accepted values: calls (default), imports, extends, implements.

mcp__mycelium__get_callers({ "path": "src/models.rs>User", "edge_kind": "extends" })
→ { "callers": ["src/models/admin.rs>AdminUser"], "count": 1 }

get_callee_tree — recursive callee tree

When: "what does my function transitively depend on?" — gives a tree, not a flat set.

mcp__mycelium__get_callee_tree({ "path": "src/auth/session.rs>AuthService>login", "max_depth": 3 })

Returns a nested { path, children: [...] } structure. Default depth 3, capped at 10. Cycles are detected and rendered as { path, cycle: true } leaves.

get_caller_tree — recursive caller tree

When: "who transitively depends on my function?" — the refactor blast-radius view.

mcp__mycelium__get_caller_tree({ "path": "src/auth/session.rs>AuthService>login", "max_depth": 3 })

get_entry_points — symbols with no incoming Calls edges

When: "what are the roots of the call graph?" — main functions, CLI commands, HTTP handlers. Combined with get_dead_symbols, gives a project-shape overview.

mcp__mycelium__get_entry_points({ "limit": 100 })

get_dead_symbols — symbols with no incoming OR outgoing Calls edges

When: "what's unreachable from anywhere?" — dead-code detection. Note: test code often appears here because tests don't call each other. Filter with --exclude-paths "tests/" if you want production-only dead code.

mcp__mycelium__get_dead_symbols({ "exclude_paths": ["tests/"], "limit": 200 })

edge_kind (v0.1.12, Issue #297) — query a specific edge kind instead of the default Calls. When set to imports, returns symbols with no incoming Imports edges (i.e. nothing imports them). Accepted values: calls (default), imports, extends, implements.

mcp__mycelium__get_dead_symbols({ "edge_kind": "imports", "exclude_paths": ["tests/"], "limit": 200 })
→ symbols that are never imported by any other file

get_isolated_symbols — singleton nodes in the call graph

When: similar to get_dead_symbols but stricter — symbols with zero edges of any kind. Often signals unused utility functions or generated code.

rank_symbols — rank symbols by edge-kind fanout (v0.1.12, Issue #297)

When: "what are the most-imported / most-extended / most-called symbols?" — importance ranking scoped to a specific edge kind.

edge_kind (required) — the edge kind to rank by. Accepted values: calls, imports, extends, implements.

mcp__mycelium__rank_symbols({ "edge_kind": "imports", "limit": 20 })
→ { "symbols": [{ "path": "src/utils.rs>helpers", "in_degree": 47 }, ...] }

mcp__mycelium__rank_symbols({ "edge_kind": "calls", "limit": 10 })
→ { "symbols": [{ "path": "src/db.rs>query", "in_degree": 132 }, ...] }

Known limitation: autouse conftest fixtures inflate caller counts

In pytest projects, conftest.py fixtures decorated with autouse=True run around every test and commonly import and call methods across many modules (resetting singletons, clearing caches, etc.). Mycelium records all of these as static call edges, so every test file appears to call every method touched by an autouse fixture — even if that test file has nothing to do with those methods.

Practical impact:

• get_callers caller counts are inflated for any symbol touched by autouse fixtures.
• get_dead_symbols / get_isolated_symbols may report code as "live" only because an autouse fixture reaches it, making dead-code detection unreliable.
• get_callers "conftest.py>reset_singletons" may show hundreds of test-file callers, obscuring actual direct callers.

Workaround: use --exclude-paths "tests/" (CLI) or exclude_paths: ["tests/"] (MCP) to restrict analysis to production code. For true test-coverage measurement (which tests actually exercise which code paths), use a runtime tool such as pytest-cov — mycelium's static call graph cannot distinguish "transitively reachable through autouse fixtures" from "directly exercised by this test".

This is a static analysis limitation, not a mycelium bug (issue #269).

Common chains

• "Where is this code reached from?" → get_callers → get_caller_tree --max-depth 5.
• "What does this function transitively touch?" → get_callees → get_callee_tree --max-depth 5.
• "Is this code dead?" → get_callers (empty?) + get_callees (empty?) → confirm via get_dead_symbols listing.
• "What's the project's entry point?" → get_entry_points --limit 50.

Equivalent CLI

mycelium get-callers "src/auth/session.rs>AuthService>login" --format=json
mycelium get-callers "src/models.rs>User" --edge-kind extends   # who extends User?
mycelium get-callees "src/auth.rs>login" --edge-kind imports    # what does login import?
mycelium get-caller-tree "src/auth/session.rs>AuthService>login" --max-depth 3
mycelium get-dead-symbols --prefix src/                         # dead by Calls+Imports (classic)
mycelium get-dead-symbols --edge-kind imports --prefix src/     # no incoming Imports

Parity contract

Per RFC-0090: each of the 7 CLI ↔ MCP pairs is byte-identical in name, description, argument schema, and JSON output. tests/parity.test.json asserts byte-equality for one input per capability against a fixture project with a small call graph.

Cross-references

• Related Skill: basic-queries — to find the symbol path first.
• Related Skill: import-graph (planned) — for Imports edge traversal.
• Related Skill: centrality (planned) — for "most called" / "most calling" rankings instead of raw sets.
• Related Skill: graph-structure (planned) — for cycle detection and dependency layers in the call graph.
• Implementation: crates/mycelium-mcp/src/lib.rs (search for mycelium_get_callers, etc.).