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

With no annotations, the description should disclose behavioral traits like whether this operation is destructive (overwrites existing identity), irreversible, or requires specific permissions. It only states that it stores the key, leaving important side effects unspecified.

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?

The description is concise: two sentences, no fluff. The first sentence states the purpose, the second adds a critical requirement. Every word is earned.

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?

Given the tool's simplicity and lack of output schema or annotations, the description provides the core functionality but omits return value information (e.g., whether it returns the public key) and whether the operation is idempotent. It is minimally adequate but not fully complete.

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?

The input schema already provides a clear description for the single parameter 'private_key'. The tool description adds the context that the key is stored and used to derive the public key, but this does not significantly enhance the schema's clarity, earning a baseline score of 3.

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 clearly states the action ('Set a Nostr identity'), the resource ('for the agent'), and what it does ('Stores the private key and derives the public key'). This effectively distinguishes it from the sibling 'get_nostr_identity' which reads the identity.

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?

The description mentions a prerequisite ('REQUIRES AGENT KEY') but does not provide guidance on when to use this tool versus alternatives (e.g., when to set vs update), nor does it explain the consequences of calling it multiple times.

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