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

Annotations declare destructiveHint=true, readOnlyHint=false and non-idempotent, yet the description frames this as a read ('Read the actual validation result'), disclosing no mutation, overwrite, or open-world fetch risk. The schema's options description admits supplied design patches can overwrite session content, but that critical warning never reaches the top-level description an agent reads first.

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 short sentences, front-loaded with the action and with zero filler. It is not under-specified in length, though the brevity is part of why behavioral caveats are absent.

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 destructive, non-idempotent, open-world tool with a nested options object and no output schema, the description omits what a 'validation result' contains, whether failure leaves the session modified, and how the returned result should be read. The schema carries some of this, but the description alone leaves an agent under-informed for a mutating 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 100%, so all four parameters are documented in the schema, including the subject/sessionToken/requestId provenance and UUID reuse rules. The description adds no parameter guidance of its own, which is acceptable at this coverage level but unremarkable.

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 ('Validate the ... design') plus a distinguishing mechanism ('with the existing production compiler'), and covers both 'current or supplied' design modes. It is separable from siblings like preview_design and save_design, though the save relationship is only implied.

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 phrase 'before saving' implies a pre-save workflow step, which is useful sequencing guidance. But it never names alternatives (preview_design, save_design) or states when validation is unnecessary, so the agent must infer the decision rule.

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