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

Annotations only supply readOnlyHint=false and destructiveHint=false; the description meaningfully adds that code 'stays in the browser', that there is 'no server-side project', and that 'nothing is deployed or charged'. Those are concrete, non-obvious behavioral facts an agent can't get from structured fields. It omits error behavior (slug collisions, plan limits) and what happens on partial failure, so not a 5.

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, zero filler, with the scope (which account, which product types) front-loaded and the safety/cost caveat following. Nothing redundant.

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 three-parameter creation tool with no output schema, the description never indicates what a successful call yields (project id, URL, slug?) — an agent cannot know what to do with the result. Combined with the incomplete product enumeration, the definition is workable but leaves notable gaps.

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 67%, with name, slug, and product already partly documented in the schema. The description gives useful meaning to the product values (Cloud site, Data project, Studio browser app, Mobile Expo starter), but that enumeration omits the fifth enum value 'code', and it never mentions slug's Cloud-only requirement beyond what the schema says. Baseline 3 is appropriate given the schema carries most of the load.

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 opens with a specific verb ('Create') and enumerates the resource variants (Cloud site, Data project, Studio browser app, Mobile Expo starter) for 'this account'. An agent can distinguish this provisioning tool from siblings like deploy or list_projects without opening the schema. It stops short of explicitly naming an alternative tool, which keeps it at 4 rather than 5.

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: 'Nothing is deployed or charged' signals this is a scaffolding step preceding deploy, and distinguishes it from a deployment tool. There is no explicit statement of when to choose create_project over 'project' or 'deploy', nor any prerequisite such as account readiness or slug availability.

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