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

Annotations declare destructiveHint=true and idempotentHint=false, but the description goes well beyond them: it explains that reading permanently destroys the secret, that hosted mode exposes plaintext briefly over TLS, that nothing is stored or logged, and offers a zero-knowledge alternative. That is exactly the added behavioral context annotations cannot 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?

Front-loads the action and the destructive consequence, then layers privacy caveats. Slightly dense with the hosting/encryption discussion, but every sentence carries information an agent needs before calling a one-time-read tool.

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 two-parameter tool with no output schema, the description covers the return value ('return the secret'), irreversibility, failure/security considerations, and the alternative deployment. Nothing an agent needs to call it correctly is missing.

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 both link and passphrase are already documented, including the #key fragment requirement. The description reinforces the link format with a concrete template but adds no new semantics for passphrase, so baseline 3 applies.

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 (open/read) and resource (one-time secret link) and says exactly what is returned. The URL template (https://.../s/{id}#{key}) makes the target unambiguous, and the tool's role is clearly distinct from ncrypted_create or ncrypted_status.

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?

Gives explicit operating guidance ('Only use the value for the task at hand and do not repeat it in chat') and tells the agent when to prefer the local server for zero-knowledge decryption. It never explicitly contrasts with sibling ncrypted_burn, so the routing between read and burn is left to inference.

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