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

Annotations already declare this is a non-readonly, non-idempotent, non-destructive write. The description adds critical non-obvious behavior: the key is returned exactly once, is prefixed 'chirpie_sk_', and is never shown again. That is exactly the kind of disclosure the description should carry.

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?

Three focused sentences, front-loaded with the action and the one-time-return warning. The scope-inheritance sentence is dense but earns its place. Slightly heavy for a two-parameter tool, but not padded.

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?

With no output schema, the description fills the gap by telling the agent the return value (the full key) is available only once. Combined with the scope rules and one-time visibility, an agent has everything needed to call this correctly.

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 coverage is 100%, so the schema already documents both parameters, setting a baseline of 3. The description goes beyond it by explaining scope inheritance: a key with no scopes mirrors the calling key, and a key can never grant a scope the caller does not hold — real semantic value the schema doesn't convey.

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 opens with a specific verb and resource: 'Create a new Chirpie API key.' This cleanly distinguishes it from sibling tools like chirpie_list_keys and chirpie_revoke_key without requiring schema inspection.

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?

It explains the semantics of scopes (what happens if you omit them, and the no-escalation rule), which implies when a scoped key is appropriate, but it never states explicit when-to-use/when-not-to-use conditions or names an alternative tool. Usage guidance is implied rather than stated.

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