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

Beyond destructiveHint=true, the description discloses the concrete consequence (the old password stops working) and the response contract (connection details returned without the password), plus the user-approval requirement implied by confirm. That is exactly the extra context annotations cannot express.

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?

Three short sentences, front-loaded with the core action and its conditional scope, then the side effect, then the response, then the alternative. No filler.

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 destructive 3-parameter write with full schema coverage, no output schema, and annotations covering safety, the description supplies the remaining essentials: what gets invalidated, what the reply contains, and where to go for other FTP-account work.

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 100% — each action, confirm, and the password format are already documented in the schema. The description adds the outcome of the change but no additional parameter syntax or constraints, so the baseline of 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?

Specific verb+resource (sets the FTP password of the active site) with the two states it operates in spelled out (none set vs. replace existing). It also names a sibling (apps_write) for the adjacent FTP-account operations, so an agent can orient it against neighbors.

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?

Clear context for both branches and a routing pointer: FTP accounts of the server environment are created/changed with apps_write, not here. It does not explicitly say when NOT to call it (e.g., prerequisite of selecting an active site), which keeps it just short of a 5; the per-action when-to-use is fully covered by the schema oneOf entries.

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