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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=true), so the bar is lower. The description still adds real context: what a blocklist means operationally ('emails that never receive email'), the endpoint, and the three possible reason codes — knowledge not present in schema or annotations.

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?

A single front-loaded sentence carries the resource, its meaning, the returned fields, and the enum values, with the endpoint appended compactly. No sentence is 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 no-required-parameter read tool with full schema coverage and no output schema, the description is nearly complete — it even names the returned fields (address, reason) and the endpoint. Only the pagination/listing semantics delegated to the schema are absent, which is acceptable.

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 limit, offset, and search are fully documented in the schema, making the baseline 3 appropriate. The description adds nothing about pagination or search behavior beyond what structured fields already state.

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 ('List') and resource ('the account's blocklist'), defines it inline ('emails that never receive email'), and enumerates the concrete reason values. It is clearly distinct from the mutation siblings emailchef_block_emails and emailchef_unblock_email.

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 read-only listing intent is implied by 'List' and the semantic gloss, but there is no explicit when-to-use or when-not-to-use guidance and no reference to the block/unblock siblings that would let an agent route correctly without inference.

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