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ctxvault

ctxvault

by Filippo-Venturini
OverviewSchemaSourceRelated ServersDiscussionsAdmin
Python
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write_skill

Create and store reusable skills in a skill vault to persist procedural knowledge, instructions, or how-to guides. Indexed by name and description so agents can retrieve and execute them later.

Instructions

Create and store a new skill in a skill vault. Use this to persist procedural knowledge, instructions, or how-to guides that agents can retrieve and execute later. The skill will be indexed by name and description for fast lookup. Use this only with skill vaults.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "vault_name": "<vault_name>",
      "skill_name": "<skill_name>",
      "description": "<description>",
      "instructions": "<instructions>"
    },
    "name": "write_skill"
  }
}

Input Schema

NameRequiredDescriptionDefault
overwriteNo
skill_nameYes
vault_nameYes
descriptionYes
instructionsYes

Output Schema

NameRequiredDescriptionDefault
filenameYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.9.1

TDQS

B3.3/5.0
Behavior3/5

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

With no annotations, the description carries the whole burden. It usefully discloses that skills are indexed by name and description for fast lookup, but it never explains what happens when a skill name already exists, what the overwrite flag destroys or replaces, or what errors a caller should expect from a write.

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?

Three short sentences, front-loaded with the action and its purpose, with no filler. The trailing vault constraint could have been folded into the first sentence, but nothing is wasted.

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?

An output schema exists, so return values need not be described. The remaining gap is behavioral and parameter-level detail for a four-required-parameter write tool with no annotations, particularly the overwrite semantics, which an agent needs before invoking it.

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

Parameters2/5

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

Schema description coverage is 0% across five parameters, so the description must supply meaning. It only hints at two of them (name and description drive indexing) and says nothing about vault_name, instructions format, or the overwrite flag's effect, leaving the majority of parameters undocumented.

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 opening sentence gives a specific verb and resource: 'Create and store a new skill in a skill vault.' That is unambiguous and readable against read_skill/list_skills, though it never names a sibling to sharpen the boundary.

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 says what content belongs here ('procedural knowledge, instructions, or how-to guides that agents can retrieve and execute later') and adds a scope constraint ('only with skill vaults'). It never states when not to use it or points to an alternative such as read_skill for retrieval, so guidance is implied rather than explicit.

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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