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

Annotations already declare non-readOnly, idempotent, non-destructive and closed-world behavior, so the safety profile is covered. The description adds platform-specific token provenance (Firebase/Apple SDK vs. PushSubscription JSON), which is genuinely useful context. It does not say what happens when the same token is re-registered for a different user, nor what the response contains.

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 sentences with no waste, and the core action is front-loaded before the format caveat. Every clause carries information the agent needs.

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 four-parameter registration tool with annotations covering the safety profile and no output schema, the description covers purpose and the trickiest parameter interaction. It stops short of describing return behavior or duplicate-registration semantics, which is a minor gap rather than a blocker.

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 75%, leaving room for the description to add value, and it does: it explains how the 'token' parameter's format depends on the 'platform' enum value (Android/iOS native SDK token vs. web PushSubscription serialized as JSON). The 'user_id' and 'name' parameters are left to the schema, which already documents them.

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?

States a specific verb and resource ('Store a device's push token') plus the scoping relationship ('under your user id'), which cleanly separates it from sibling read/removal tools like list_devices and remove_device. An agent can identify the operation without opening the schema.

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?

Usage is implied by the resource (register a device so it can receive pushes), but there is no explicit when-to-use framing, no mention of prerequisites such as obtaining a token first, and no reference to the sibling alternative remove_device for the inverse operation. Adequate but leaves the agent to infer the workflow.

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