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

Annotations declare destructiveHint=true and idempotentHint=false; the description usefully adds that omitting projectId always creates a new project (explaining the non-idempotent behavior) and that no export access is required. It stops short of warning what may be overwritten/destroyed when an existing projectId is supplied, which is the key risk implied by destructiveHint.

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, zero filler, with the primary action stated first and the conditional parameter rule immediately after. Every sentence carries distinct information.

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?

An output schema exists, so return values need not be described. The description covers the account-scoped save, the update path, and the permission requirement, though it omits what an update does to an existing saved design, which matters given the destructive annotation.

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 the schema already documents both parameters and the whole nested settings tree. The description reinforces the projectId omit-vs-pass rule but adds no formatting or behavioral detail beyond what the schema description already says, so 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?

The description states a specific verb and resource ('Save the provided complete design in the connected NameSTL account') and clarifies the create-vs-update branch driven by projectId. It does not distinguish itself from the sibling create_design, which an agent could reasonably confuse with the 'creates a new project' path described here.

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?

It gives an explicit conditional for the optional parameter: pass projectId only when the user asked to update that saved design, otherwise a new project is created. It also notes that saving does not require export access, implicitly steering away from check_export_access, but it never names the alternative tools (create_design, export_design) that an agent might otherwise pick.

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