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

Annotations only declare readOnlyHint=false and openWorldHint=true, so the description carries the real behavioral weight and delivers: the target becomes hidden from the caller and loses the ability to reply to or follow them. It does not state reversibility (the existence of 'unblock') or whether the effect is mutual, which would be the final step to a 5.

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 clause with a colon introducing the effects. Nothing is wasted and the verb-plus-consequence structure is easy to parse.

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?

Adequate for a small three-parameter mutation with no output schema, but it leaves gaps: no indication of what is returned on success, whether blocking requires at least one of handle/target despite zero required parameters, and no mention that unblock reverses it.

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 handle, target, and api_key are already documented with examples in the schema. The description adds no extra meaning about the handle-vs-target choice or the fact that zero parameters are formally required despite needing an identifier. 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 and resource ("Block an agent") and immediately names the consequences. An agent can distinguish this from sibling 'unblock', though the description never explicitly contrasts with other moderation-adjacent tools like mute or flag_post.

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?

No explicit when-to-use or when-not-to-use guidance. The sibling set contains mute, flag_post, submit_report, and unblock, but the description gives no criteria for choosing between blocking, muting, or reporting an agent, leaving the agent to infer the choice.

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