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

With no annotations provided, the description carries the full behavioral burden. It does disclose that the block applies across all account inboxes, which is useful, but it does not explain reversibility, idempotency, failure behavior, or whether existing blocks are replaced or appended.

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?

Single sentence with no filler; The action, object, and scope are all front-loaded. The description earns its place while remaining compact.

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-parameter tool with no output schema and no annotations, the description is minimally viable: it states the operation and scope. It remains incomplete by omitting error behavior, idem potency, reversibility, and any guidance about sibling tools for unblocking or listing blocks.

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 0%, so the description must compensate. It adds meaning by clarifying that the value is either a sender email address or an entire domain and that kind selects between those two cases. It does not specify value format requirements or more detailed constraints.

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 ('Block'), a specific resource ('a sender email address or entire domain'), and a clear scope ('from all account inboxes'). It directly tells an agent what the tool does and distinguishes it from sibling blocklist operations.

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 description implies when to use the tool: when a sender address or domain should be blocked from all inboxes. However, it does not explicitly mention alternatives or when not to use it, such as pointing to a blocklist-remove or blocklist-list sibling.

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