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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so the safety profile is fully covered. The description adds only that output is 'production-ready' and includes a token estimate; it says nothing about how components are composed, whether unspecified fields are omitted or defaulted, or what the token estimate applies to. Useful but thin extra context.

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 tight sentences: the first front-loads the input components, the second states the output and the token estimate. No filler, no redundancy.

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 an output schema present, return values need not be explained, and the annotations cover safety, so the description is largely sufficient for correct invocation. The remaining gap is sibling routing — nothing tells an agent to prefer this over build_rag_prompt or prompt_template_fill.

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% and each of the seven properties is documented, including an enum for tone, so the schema carries the semantics. The description merely restates the same field names without adding format hints, defaults, or guidance such as what 'examples' expects as a string versus a list. Baseline 3 is appropriate.

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 ('Build a structured system prompt') and enumerates the component inputs (role, task, constraints, output format, tone, language, examples), so an agent knows exactly what it produces. It does not differentiate itself from near-siblings such as build_rag_prompt, few_shot_formatter, or prompt_template_fill, which an agent would need to disambiguate.

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?

Usage is only implied: the component list suggests 'use this when you need to assemble a system prompt from parts', but there is no explicit when-to-use, no prerequisites, and no named alternative among the many prompt-related siblings. An agent can infer the context but must guess at routing.

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