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

Annotations only declare readOnlyHint=false, destructiveHint=false, openWorldHint=false. The description adds substantial behavior beyond that: the fork semantics of template_id (sources, staged transactions and mapping rules copied under fresh ids, connector credentials excluded), the plan-cap rejection, and the key-scope restriction. These are exactly the non-obvious traits an agent needs before invoking a mutation.

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?

Front-loads the core purpose and return value, then handles parameters in a single dense parenthetical. The glyph example list (SaaS trending-up, banking landmark, real estate house, coffee shop coffee, energy wind, HR users, valuation scale, treasury wallet) is longer than needed and partly duplicates the schema's own glyph examples, which costs some efficiency.

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 and thin annotations, the description carries most of the burden and does so well for a 5-parameter nested-object tool: it covers the return value, fork side effects, hard limits, and credential exclusions. Remaining gaps are secondary (subtitle semantics, timeline defaults/structure), not enough to block a correct call.

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 only 20%, so the description must compensate, and it largely does: template_id's fork behavior and timelines' bounds-setting role are explained in prose even though neither parameter is documented in the schema. subtitle is never explained, and the internal structure of timelines (yearly/monthly/quarterly) is not described, leaving a modest gap.

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 and resource ('Creates a model') and adds the return shape ('returns its detail with its UUID'), which is useful since no output schema exists. It does not explicitly distinguish itself from the other creation-flavored sibling layerz_build_from_blueprint, so the boundary is left to inference.

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 gives real preconditions ('Rejected past the plan model cap', 'Not advertised to model-scoped or read-only keys') which tell the agent when the call will fail, but it never says when to prefer this over layerz_build_from_blueprint or other sibling creation paths. Usage is implied rather than routed.

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