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

Annotations already cover idempotency and non-destructiveness, and the description adds context those annotations cannot express: the @-based email/domain interpretation rule, the fact that a value can be converted between forms, and that a global-scope change both requires the main workspace key and relocates the entry onto the main workspace. That side effect and auth requirement are exactly what an agent needs before mutating.

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?

Three tight clauses, front-loaded with the core action before the interpretation rule and the global-scope caveat. Dense but every sentence carries information; the parenthetical enumeration of "global" is slightly redundant with the schema enum.

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 three-parameter mutation tool with no output schema, the description covers the operation, the required-at-least-one rule, value interpretation, and the global-scope side effect. It does not address failure behavior (e.g. an unknown id), a minor 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 coverage is 100%, so the baseline is 3, but the description adds real meaning the schema lacks: the at-least-one-of constraint between value and scope, the @ rule governing how value is interpreted, and the behavioral consequence of scope="global". The enum values themselves are already documented in the schema.

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 opens with a precise verb+resource+scope: it changes one blocklist entry's value, scope, or both. A reader can immediately separate it from add_blocklist_entries and remove_blocklist_entry, which create and delete rather than mutate in place.

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?

It states the operative constraint ("provide at least one" of value/scope) and the prerequisite for the global case (main workspace's key). It does not explicitly route the agent toward alternatives such as remove_blocklist_entry when the intent is deletion, so guidance is clear but not exhaustive.

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