spawn

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

Annotations only say readOnlyHint=false and destructiveHint=false; the description adds meaningful context beyond that: execution is restricted to an allow list ("nothing else can run"), the window must be awaited, and failure is diagnosable via program_output. It does not say whether the process persists after the session ends or what happens on repeated spawns of the same program.

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 action and its constraint, followed by the required next step and the failure path. No filler, and each sentence carries a distinct instruction.

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, the description covers the outcome sufficiently: either the window comes up (then wait_for it) or program_output explains the failure. For a 2-parameter, fully documented launch tool this is complete enough to call correctly.

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%, so both parameters (program, session) are already documented, including the enum constraint on program. The description's "by its name, in a session" adds only light reinforcement of what the schema states, so the baseline 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?

States a specific verb ("Start") and resource ("one of the programs the person allowed this server to run") plus the scoping constraint that nothing else can run, which distinguishes it from the input/interaction siblings. It also names the downstream tools (wait_for, program_output), so an agent can place it correctly in a sequence 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 prescribes the follow-up flow: wait_for the window before looking at it, and use program_output if the program doesn't come up. There is no sibling alternative to spawn, so no exclusion is needed, but it stops short of stating prerequisites (e.g., that a session from start_session must already exist, which is only implied by the session parameter).

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