ws:Close — close a WebSocket and free its slot

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

Annotations already declare destructiveHint=true, idempotentHint=false, readOnlyHint=false, so the mutation profile is known. The description adds real value beyond that: the underlying call is pcall-wrapped, the entry is marked closed and removed from the getgenv registry, and unknown ids are guarded to return { error }. The 'MUTATING; external network/socket I/O' line largely restates annotations, keeping it from a 5.

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?

The operational content is front-loaded and useful, but the description is padded with metadata boilerplate (Phase, cost, idempotency, Capabilities, Produces, Safety) that duplicates annotation-provided facts. Several of these clauses do not earn their place, diluting an otherwise efficient opening.

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 mutation tool with no output schema, the description supplies the return shapes ({ id, closed = true } or { error }), the failure/guard behavior, prerequisites (active-client, getgenv, ws-connect entry), and a verification path via ws-list. Nothing an agent needs to invoke 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 parameters (id, threadContext) are already fully documented in the schema. The description echoes the signature but adds no syntax or format meaning beyond what the schema provides, matching the baseline 3.

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+resource ('closes a WebSocket') and immediately scopes it to sockets 'previously opened with ws-connect, addressed by its registry id'. An agent can distinguish it from ws-connect, ws-send, ws-receive, and ws-list 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?

Gives a clear precondition (must be opened via ws-connect, entry comes from that call) and names ws-list as the verification step. It does not explicitly state when-not to use it or name a competing alternative, so it falls short of a 5.

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