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

Annotations already declare destructiveHint=true, idempotentHint=true, and openWorldHint=true. The description adds meaningful context beyond them: account-wide blast radius ('any list'), the 100-address cap, reversibility via emailchef_unblock_email, and the underlying POST /blockings?type=MANUAL endpoint. It does not cover failure modes or partial-success behavior for batch input.

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 plus an endpoint fragment, all front-loaded — operation type first, effect and reversibility next, endpoint last. No sentence is redundant.

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 single-parameter mutation with rich annotations and no output schema, this covers operation, scope, limit, and reversal path. The only unaddressed elements are the response shape and what happens when some addresses in the batch are already blocked, which are minor here.

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% and the single parameter already documents the email format, per-item maxLength, minItems, and maxItems=100. The description echoes the 100-address limit and clarifies the blocklist is account-level rather than list-specific, but adds no syntax or format detail beyond the schema, so baseline 3 applies.

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 (add/block) and resource (account blocklist), with explicit effect scope ('never receive email from any list'). The 'WRITE:' prefix and the pointer to emailchef_unblock_email distinguish it from read-oriented siblings like emailchef_list_blocked.

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 a clear use context (suppress delivery across every list) and names the reversal tool, so the agent knows the counterpart operation. It stops short of stating when NOT to use it (e.g. per-list suppression vs unsubscribe), so it is not a full 5.

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