There is no protocol-wide standard list of MCP memory-server tools. MCP specifies how clients discover and call tools; each server chooses which tools it provides. The official reference memory server documents nine knowledge-graph tools, but other servers may expose a different set.
What does MCP standardize?
MCP standardizes tool discovery and invocation, not a fixed set of memory operations. Under the current specification, a server that declares the tools capability must answer tools/list requests with the tools currently available to the requesting client. The list may be empty, can change, and may depend on the authorization in the request. See the MCP tools specification.
That means “standard tools” can refer to two different things: the MCP protocol’s tool mechanism, or the tool names in a particular implementation. The protocol does not require every memory server to implement the reference server’s names or behavior.
Which nine tools does the reference memory server document?
The official MCP reference memory server models memory as a knowledge graph of named entities, types, observations, and relations. Its README documents these nine tools:
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| Tool | Purpose in the reference server |
|---|---|
create_entities |
Creates multiple entities, each with a name, type, and observations. Entities whose names already exist are ignored. |
create_relations |
Creates relations between existing entities. A relation has a source, target, and active-voice relation type. Duplicate relations are skipped; creation fails if either endpoint does not exist. |
add_observations |
Adds observations to existing entities. Observations are strings and should be atomic—one fact per observation. |
delete_entities |
Removes entities and their associated relations. |
delete_observations |
Removes specified observations from entities. |
delete_relations |
Removes specified relations from the graph. |
read_graph |
Returns the complete graph structure, including entities and relations. |
search_nodes |
Searches entity names, types, and observation content, returning matching entities and relations. |
open_nodes |
Retrieves named entities and relations between requested entities. Nonexistent names are silently skipped. |
The list divides naturally into three creation or update tools, three deletion tools, and three graph reading or retrieval tools. The official Go SDK memory example also registers these nine tools. That corroborates them as a project example, not as a requirement for MCP servers generally.
How should a client find the tools a server actually supports?
Use MCP tool discovery against the connected server rather than assuming it has the reference implementation’s tool names. The returned list represents the tools currently available to that client and request, so it is the relevant source for integrations that need to handle differences between servers or authorization states.
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Are the graph resource and update notifications tools?
No. The reference server also provides a readable memory://knowledge-graph resource containing the graph as JSON. Its README says successful graph mutations notify subscribers that the resource has been updated. Resources and update notifications are complementary MCP features; they are not additional entries in the nine-tool list. See the reference server documentation.
What to verify when choosing an implementation
If you are assessing an MCP memory server for an integration, check the server’s live tool list and documentation for the details that matter to your client:
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- Which tool names and input schemas it advertises.
- What memory data model it uses and how reads, updates, and deletions behave.
- How persistence and authorization work.
- Whether it exposes resources or update notifications in addition to tools.
The reference server’s nine-tool list is a useful baseline for understanding one knowledge-graph design, but it is not a compatibility guarantee for other implementations. Tool names and behavior can change as a project evolves; the specification and repository documentation reviewed for this article were current on October 4, 2026.
Quick Recap
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