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

readOnlyHint=true already tells the agent this is a safe read. The description adds mapping value ('GET /entities') and encodes the wire behavior of the status filter ('sent as status.in'), which is real context beyond the annotations. It stops short of describing pagination semantics or the shape of returned entity records.

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 compact sentences, front-loaded with the resource definition, then endpoint, then filter behavior. Nothing is padded, though the endpoint string and the parenthetical overlap slightly in what they convey.

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 read-only list tool with 100% schema coverage the description is adequate, but with no output schema an agent gets no hint of what entity records contain or how pagination terminates — only that a cursor exists in the schema. It covers purpose and filtering but leaves return-shape expectations unaddressed.

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 100%, so limit, cursor, and status are all documented in the schema itself. The description only restates the status filter's transmission format ('sent as status.in'), adding slight encoding detail but no new semantics for limit or cursor. Baseline 3 applies when the schema does the heavy lifting.

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?

Specific verb+resource ('List entities') with a useful domain gloss: 'the people/businesses — KYC records — that own accounts', which tells an agent what an entity is. The API endpoint mapping (GET /entities) reinforces it. It does not explicitly differentiate from siblings like increase_list_accounts, but the resource noun alone is distinctive enough to select correctly.

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?

No statement of when to use this tool, when not to, or which sibling to prefer (e.g., use list_entities to enumerate KYC owners vs list_accounts for accounts). The only guidance is a filter hint ('Filter by status'), which is parameter behavior, not usage context.

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