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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds the useful scoping fact that results are limited to portfolios administered by the connected account, but says nothing about pagination, result shape, or auth/permission requirements beyond the connection.

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 with zero filler; the resource and scope come first and the relationship to ads_create_account is a genuinely load-bearing second sentence.

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, zero-required-param list tool with fully documented parameters and annotation-covered safety, this is nearly complete. The only real gap is the absence of return/pagination expectations, which matters slightly since no output schema exists.

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% and both parameters (accountId, profileId) are already documented with defaults in the schema, so the description carries no additional parameter burden. It adds nothing beyond the schema, which is the expected baseline rather than a strength.

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 (List) and resource (Business portfolios) with an explicit scope qualifier: portfolios 'the connected Facebook account administers'. It also positions itself relative to ads_create_account, so an agent knows both what it returns and why it matters.

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 second sentence gives a concrete when-to-use trigger: call this before ads_create_account because ad accounts can only be created inside one of these portfolios. It does not, however, name ads_list_accounts as the distinguishing alternative or state any when-not condition.

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