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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=false, so safety is covered. The description still adds value beyond them by disclosing the return shape ({ id, name, website, kind }) and the cardinality-driven prerequisite for other tools. It does not mention ordering or any cap on list size, but for a closed-world read of a small account-scoped collection that is a minor gap.

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 sentences, front-loaded with the verb and resource, with the prerequisite guidance second. The inline brace notation for the return shape is slightly telegraphic, but no sentence is filler.

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?

No parameters and no output schema, so the description carries the return-shape burden itself and does so, listing the four fields. Combined with the annotations and the explicit role as the entry point for multi-project accounts, an agent has everything needed to call it and use the result.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The description instead spends its words on output fields, which is the right use of space here.

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 ('Lists the account's projects') and immediately disambiguates what a project is ('each a business Marsell markets'), which no sibling name conveys. An agent can distinguish this enumeration tool from get_brand/get_market or business_read without opening any schema.

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?

Explicitly says when to call it ('Start here when there is more than one') and explains the downstream contract: every other tool takes project by id or exact name and may omit it only when the account has one. That is genuine when-to-use plus the alternative/omission condition, not implied guidance.

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