ddflow_companions_add

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

No annotations are present, so the description carries the full disclosure burden. It does so by revealing the merge-not-overwrite behavior, the exit 3 refusal for non-installed servers, and the reason (a launch command that fails mid-task). This is meaningful behavioral information beyond what the schema alone shows.

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 front-load the action and merge semantics, and the second justifies the hard-failure behavior without repetition. No filler words or restatements of the tool name.

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 two-optional-parameter tool with no output schema, the description covers the essential invocation context: target state (already installed), behavior on conflict (merge), and failure mode (exit 3). It does not describe the success return or configuration side effects, but those are minor against the clear usage boundary.

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%, with both id and agents already described inline. The description adds no parameter-level detail beyond the schema, 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?

The description names a specific action ('Register companion MCP servers'), qualifies the target ('ALREADY installed'), and states the merge behavior that distinguishes it from overwrite-style configuration tools. This is enough to separate it from the ddflow_companions family and other config-related siblings.

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?

The opening clause sets the appropriate condition: this tool is for servers already present in the agent's MCP config. It also gives an explicit when-not signal by stating it refuses (exit 3) to register non-installed servers, with the failure rationale. It does not name an alternative tool, but the inclusion/exclusion boundary is clear.

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