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mem_session_start

Idempotent

Create or reuse a memory session by unique ID, enabling persistent storage and automatic recall of coding decisions, fixes, and conventions for AI agents.

Instructions

Create a memory session, or return it unchanged if its identifier exists.

Input Schema

TableJSON Schema

Name	Required	Description
`id`	Yes	Unique session identifier. Also accepted as `session_id`, which is what every tool that writes to a session calls it.
`project`	No	Optional explicit project; otherwise it is detected from directory or cwd.
`directory`	No	Working directory for this session.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`session`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Aug 11, 2026

TDQS

A3.6/5.0

Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already provide idempotentHint=true, and the description essentially restates that with 'return it unchanged if its identifier exists.' It adds minor specificity but no deeper behavioral context such as side effects or prerequisites. No contradiction with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

A single, front-loaded sentence that conveys the core action and idempotent behavior with zero wasted words. Excellent structure.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple, idempotent create tool with full schema descriptions, annotations, and an output schema, the description is sufficient. It could have mentioned typical usage context (e.g., as a setup step before using memory tools), but that is not essential.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100% and every parameter has a description. The tool description adds no additional meaning to the parameters, just uses the word 'identifier' which maps to the required 'id'. Baseline of 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's function with a specific verb ('Create') and resource ('memory session'), and it distinguishes behavior via the idempotent clause 'or return it unchanged if its identifier exists.' This sets it apart from siblings like mem_session_end and mem_session_summary.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

No explicit guidance on when to use this tool versus alternatives. It does not mention mem_session_end for closing sessions or any other sibling, and there are no stated prerequisites or contextual triggers.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.