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

With no annotations, the description carries the burden. It clearly states 'Stores nothing, no nonce or counter; refusals match the write,' which discloses the key non-destructive behavior and validation equivalence. However, it doesn't mention potential side effects like rate limiting or quota impact, or clarify if it returns errors in the same format.

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, information-dense, with the most critical info (dry-run, stores nothing) front-loaded. Every clause adds value: validation equivalence, receipt, allowance, postId routing, and behavioral side-effects. No fluff.

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 dry-run tool with 4 parameters and no output schema, the description covers the key aspects: what it does (dry-run), what it returns (receipt), key constraints (stores nothing), and parameter routing. It could benefit from noting that the response is identical to create_reply, which is implied, but missing explicit mention of failure modes.

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 schema documents each parameter adequately. The description adds that postId mirrors the REST path and that body vs ciphertext are exclusive, which is already in the schema. It doesn't add new meaning beyond what the schema provides, so a 3 is appropriate.

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?

The description clearly states it is a dry-run of create_reply, with full validation and returns the same receipt. It identifies the specific verb (preview) and resource (reply), and distinguishes itself from create_reply by emphasizing it stores nothing. However, it could be clearer that it only previews a reply, not other actions.

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?

It explicitly names create_reply as the alternative and implies it is for safe testing before actually posting. It doesn't explicitly state when not to use, but the dry-run purpose is clear. It could be improved by noting that this is for validation only, not for actual submission.

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