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claude_update_persistence

Update persistent configuration sections in agents, projects, or memory files by replacing or appending content at a specified anchor.

Instructions

Replace or append to a section in one of the persistence files.

Required: file, section_anchor, new_content. Optional: mode (replace|append) — replace the entire section vs append inside it (default replace).

Safe-mode constraint: in Settings.mode == "safe", updating AGENTS.md requires confirm=true. Returns matched=true when the section_anchor was found; matched=false when the anchor was not found and no edit happened (so you can detect typos before silent appending).

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "claude_update_persistence"
  }
}

Input Schema

Name	Required	Description	Default
`req`	No

Output Schema

Name	Required	Description	Default
`file`	Yes
`matched`	Yes
`new_size_bytes`	Yes
`section_anchor`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.2.0Sep 20, 2026

TDQS

A3.8/5.0

Behavior4/5

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

With no annotations, the description carries the burden, and it does well: it discloses the safe-mode constraint, the default mode, and the exact matched=true/matched=false return semantics including that no edit happens when the anchor is not found. It does not discuss destructive risk beyond the word 'replace' or atomicity/ordering details, but the key failure behavior is exposed.

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

Conciseness4/5

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

The description is front-loaded with the primary action and uses short labeled lines for required/optional/safe-mode/return behavior. Each section adds information, though the safe-mode paragraph is slightly dense.

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 mutating persistence tool with no annotations, it covers the essential edge cases: anchor not found, safe mode, mode default, and return signal. An output schema exists for the return shape, so not explaining all return fields is acceptable. The nested req wrapper is the main missing call-construction detail.

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

Parameters4/5

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

Schema coverage is 0%, so the description must explain parameters, and it does: it defines mode's replace vs append behavior, explains when confirm=true is required, and clarifies section_anchor matching. The only gap is that it lists file/section_anchor/new_content as top-level required inputs while the schema nests them under a req object, which could confuse an agent constructing the call.

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

Purpose4/5

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

The description opens with a specific verb+resource: 'Replace or append to a section in one of the persistence files.' This clearly conveys the tool's core operation. It does not explicitly distinguish itself from the sibling claude_append_persistence, but the mode parameter partially covers that overlap.

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

Usage Guidelines3/5

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

It lists required and optional parameters and explains the safe-mode confirm condition, which is actionable guidance. However, it does not say when to prefer this tool over claude_append_persistence or other persistence tools; the alternative routing is left implicit.

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

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