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

Annotations already declare idempotentHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description adds one security-relevant constraint beyond the annotations: only the public key is registered. It says nothing about auth requirements, error behavior, or what happens on re-registration.

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?

A single front-loaded sentence with no filler; the key constraint leads. It is arguably too terse for a 3-parameter cryptographic operation, but there is no wasted wording.

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?

An output schema exists so return values need not be described, but with 0% schema coverage the description should compensate for undocumented parameters and the public-key format. An agent cannot confidently call this without guessing what contextId and deviceId should contain.

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 0% and all three parameters are required, yet the description explains none of them. It hints that publicKey is a public key, but deviceId and the rigid 43-character contextId are left entirely unexplained, including expected encodings.

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 ('Register') and resource ('public encryption key ... for this user's panel'), which is clear on its own. However, it does not distinguish itself from the sibling panel_sync_device_keys, which sounds like it may also register device key material.

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?

No statement of when to use this versus panel_sync_device_keys or panel_start_chat. The word 'only' hints that private key material must not be sent, but that is an inference, not guidance.

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