add_to_blocklist

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

Annotations already declare a non-destructive, open-world mutation (readOnlyHint=false, destructiveHint=false), so the safety profile is partly covered. The description adds real context beyond that: the effect spans all aliases and accepts either full addresses or whole domains. It stops short of the operationally relevant facts — whether existing delivered mail is affected, whether re-adding an existing entry errors or is idempotent, and what the response contains.

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 sentence with the verb, the accepted inputs, and the scope front-loaded. Nothing is redundant or padded.

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 full schema coverage and annotations covering safety and openness, the description supplies the purpose and cross-alias scope an agent needs to select it. Only edge-case behavior (idempotency, effect on already-delivered mail) is left unstated, which is a minor gap at this complexity level.

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 both properties and the enum are fully documented in the schema; baseline 3 applies. The phrase "email addresses or whole domains" loosely echoes the type enum but adds no format, normalization, or duplicate-handling detail beyond what the schema already provides.

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 ("Block") and resource ("mail from sender email addresses or whole domains") plus a scope modifier ("across all aliases"). That scope detail meaningfully separates it from an alias-scoped block, though it never names the sibling that reverses the operation (remove_from_blocklist) to sharpen the contrast.

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 the tool applies (blocking senders for every alias at once), but it gives no explicit when-to-use versus remove_from_blocklist or list_blocklist, and no prerequisites or exclusions. Usage is inferable from the name and scope phrase rather than stated.

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