Read the value stored for a key in a Workers KV namespace. Returns the raw stored value.
Read the value stored for a key in a Workers KV namespace. Returns the raw stored value.
| Name | Required | Description | Default |
|---|---|---|---|
| key | Yes | required,The key whose value to read | |
| account_id | Yes | required,The ID of the Cloudflare account | |
| namespace_id | Yes | required,The ID of the KV namespace |
Changes observed during successful MCP inspections.
v0.3.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description must carry the full behavioral burden. It only states that the raw stored value is returned; it says nothing about permission requirements, behavior when the key is missing, value size/type constraints, or read consistency.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two tightly written sentences, front-loaded with the action and resource, with zero wasted words. The second sentence usefully clarifies the return shape in minimal space.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple three-parameter read tool with no output schema, the description covers the core purpose and roughly what is returned. It is missing enough behavioral context (auth needs, missing-key behavior) that an agent would still need to infer or discover important operational details.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the three required parameters (key, account_id, namespace_id) are already fully documented in the schema. The description adds no parameter-specific meaning beyond what the schema provides, which is the baseline expectation.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states a specific verb (Read) and resource (the value stored for a key in a Workers KV namespace), which separates it from metadata-oriented siblings like get_kv_metadata. However, it does not explicitly name an alternative tool, so sibling differentiation is left implicit rather than stated.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
There is no guidance on when to use this tool versus get_kv_metadata, get_kv_pairs_bulk, or list_kv_keys. The purpose implies a read of a single key's value, but no conditions, prerequisites, or exclusions are given.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.