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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the description does not need to re-establish basic safety. The description adds value by specifying the response content (blocked domains/company names and match rules) and reinforcing the no-mutation trait despite the annotation coverage.

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, with the core listing behavior front-loaded and the read-only constraint stated immediately. Every clause contributes useful information and there is no redundancy or filler.

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 low-complexity list tool with zero required parameters and full schema coverage, the description is nearly complete. It identifies the resource, scope, read-only behavior, and return content. The only notable gap is that it does not clarify how it relates to 'check_blacklist', but that is more of a usage-guidance concern than a completeness gap.

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 limit, query, and offset. The description adds no additional parameter-level meaning beyond the high-level listing behavior, which is the expected baseline when the schema covers all parameters.

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?

Description states a clear verb and resource: 'List the authenticated user's company-wide blacklist.' It further specifies what is returned (blocked domains/company names and match rules) and explicitly notes it cannot add or remove entries, distinguishing it from any mutation-style blacklist tool.

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 clearly conveys the read-only scope and states that it cannot add or remove entries, which implies when to use it for viewing. However, it does not mention the sibling tool 'check_blacklist' or any alternative for checking a single domain/company, so explicit when-to-use vs alternatives guidance is missing.

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