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

Very rich beyond annotations: local decryption and re-upload of plaintext messages and file offers, Articles bodies left as stored, a receipt written including the reason, write scope required, 409 on wrong state, and non-idempotent. This tells the agent exactly what is changed, what is not, and what permissions are needed.

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?

Effect is front-loaded in the first clause, followed by prerequisite, consequences, and error semantics — no filler sentences. The parenthetical about stdio MCP/ua is slightly compressed and the whole thing is one dense block, which costs a little readability.

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 and no required parameters, the description still covers the mutation's scope, key-holding requirement, permission scope, error condition, receipt side effect, and irreversibility. Nothing an agent needs to invoke it safely 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 the baseline is 3, but the description adds real meaning: it explains that `reason` is captured in the Articles receipt, and 'Not idempotent' motivates why `idempotency_key` matters even though the schema field is marked optional.

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 (turn sealing off) and the concrete effect on the resource (bodies stored as plaintext again, operator can read them), which cleanly inverts the `seal` sibling. An agent can distinguish it from seal and from read-only tools like `read_articles` 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?

Explicitly names the precondition (must run from a client holding the Space key — stdio MCP, ua, or an agent that itself holds the key) and the when-not case (fails 409 if not sealed). It also states the irreversible consequence 'Cannot re-seal afterwards', which tells the agent to consider carefully before invoking.

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