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

With annotations already indicating destructiveHint and openWorldHint, the description adds valuable context: the result is a new content-addressed model 'you own', lineage is recorded when composing onto an existing id, and attach fuses ports. It does not contradict annotations and expands on the operational behavior.

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 sentences, each packed with useful information: core action, key parameter semantics, and a worked example. No fluff, front-loaded with the main purpose, and the example at the end reinforces usage without bloating.

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?

Given the complexity (6 params, no output schema), the description covers main usage patterns, attach mechanics, prefixes, and an example. It does not state the return value or error conditions, but the annotations and parameter schemas fill much of the gap, making this sufficiently complete.

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%, but the description adds operational semantics beyond the schema: 'omit id to start fresh', 'name kept from the base', attach maps port names to existing place ids, and prefix defaults to the component name. This meaningfully clarifies how parameters interact in the composition workflow.

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 states a specific verb (instantiate/compose) and resource (registry component into a model), and clarifies it stores a NEW content-addressed model with lineage. It distinguishes itself from siblings like sim_create_model or sim_extend by emphasizing 'registry component' and 'compose onto an existing id'.

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 description provides clear when-to-use guidance: omit id to start fresh, pass attach to fuse a component port onto existing places, and uses a concrete three-call helpdesk example. It does not explicitly name alternative sibling tools or exclusions, but the context is strong.

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