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

Annotations already declare readOnlyHint=false, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds two useful behavioral facts beyond them: the update is partial ("Only the supplied fields are changed") and the platform is immutable here. It says nothing about permissions failures, error behavior, or what is returned, so it earns credit without being rich.

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 tightly written sentences, front-loaded with the action and scope, with the mutation constraint placed second. No filler or restatement of the title; only the missing pointer to return behavior keeps it from being exemplary.

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 5-parameter partial-update mutation with full schema coverage and rich annotations, an agent has what it needs to call it correctly. The remaining gap is that no output schema exists, yet the description says nothing about what an update returns (the updated account object vs. a status), leaving that to inference.

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%, so the schema already documents every field, including the platform-specific rejection rule for google_email and the slot UUID reference. The description adds only the collective notion of optional partial fields and the absence of a platform parameter, which is marginal beyond the schema.

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 uses a specific verb and resource ("Update a posting account") and scopes it to the three supported platforms (TikTok, Instagram, YouTube). It does not explicitly name or contrast with siblings like create-account-tool or delete-account-tool, but the verb makes the distinction self-evident.

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 context is implied rather than stated: it targets accounts "the authenticated user is allowed to manage" and excludes platform changes. There is no explicit routing guidance (e.g., use create-account-tool to add one, get-account-tool to read) and no stated prerequisites for obtaining account_id.

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