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

Annotations declare destructiveHint=true and idempotentHint=false, and the description reinforces and extends this: 'This destroys it permanently', 'Free', plus a security disclosure that hosted mode decrypts the plaintext over TLS and a pointer to a zero-knowledge local server alternative. This goes well beyond what the annotations convey.

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-loaded with the action and the destructive consequence, then routing, then security context. Every sentence carries functional information, though the hosted-vs-local-mode paragraph makes it longer than strictly needed for a two-parameter 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?

Covers the irreversible consumption of the link, the return value ('return the secret'), privacy handling of the plaintext, and an alternative deployment for zero-knowledge use. Despite no output schema, nothing material is missing for correct invocation.

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 parameters are already documented, including the #key fragment and conditional passphrase. The description explains the link format inline but adds no syntax or semantics beyond the schema, so the 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 concrete verb+resource ('Open an ncrypted link ... and return the secret') and names the exact sibling it is not (ncrypted_status). An agent can distinguish it from ncrypted_burn/create/status without opening any 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?

Explicit routing: use this to consume a link, use ncrypted_status instead when only checking whether a link was opened, and it notes status 'doesn't consume anything'. It also gives a usage constraint on the result ('only use the value for the task at hand').

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