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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint false, so safety is covered. The description adds genuinely useful context beyond that: the returned fields (id, name, currency) and the default-platform behavior. It does not address pagination or what happens if no accounts are connected, and the cross-platform vs single-platform wording is ambiguous.

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 compact sentences, front-loaded with the scope statement. The value is slightly diluted because the second sentence partially contradicts the first, making the reader re-read to determine aggregation behavior.

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 two-optional-param, read-only listing tool with no output schema, the description covers the platform dimension, aggregation scope and return fields. The one real gap is resolving whether results span all platforms or just one, which matters for how the agent presents results.

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%, with enum and 'default meta' documented in the schema itself, so the schema carries the weight. The description restates the platform default but says nothing about the `search` filter beyond the schema's own 'Filter on the name'.

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 'List' plus resource 'ad accounts' and an explicit scope (Meta/TikTok/Snapchat, across all brands and clients), which separates it from siblings like list_pages or list_instagram_accounts. It loses a point because the two sentences state different scopes: the first implies all platforms in one call, the second says one platform with Meta as default.

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?

Gives an entry-point instruction ('Start here') and a disambiguation rule ('ask which one when there are several'), which is actionable agent guidance. It stops short of saying when *not* to use it or naming a concrete alternative sibling.

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