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

Annotations already declare destructiveHint=true and idempotentHint=true, so the safety profile is covered. The description adds genuinely useful context beyond that: the replacement preserves ID, type and unchanged settings, sibling blocks are untouched, and no launch occurs. It does not mention revision/conflict behavior, so a 5 is unwarranted.

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?

Four short sentences, each earning its place, with the core action and the alternative front-loaded. No filler or redundancy.

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 destructive mutation tool with an output schema and covering annotations, the description supplies the prerequisite, the alternative, the replacement scope, and the no-launch guarantee. The only gap is revision-conflict handling, which the schema notes are auto-resolved, so nothing critical is missing.

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 75%, so the baseline is 3, but 'replace one complete block' clarifies that the block parameter is a full replacement rather than a partial patch — a non-obvious semantic the schema's structure alone does not state. The construction and expectedRevision parameters get no additional description, keeping it from a 5.

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 ('replace one complete block') and immediately scopes it ('preserving its ID, type and all unchanged settings'). It explicitly differentiates itself from the sibling update_task, so an agent can route correctly without opening any schema.

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?

Gives a clear prerequisite ('Read get_test_definition first'), an explicit alternative for the common case ('Prefer update_task for task wording'), and scope boundaries ('Other blocks are preserved. No launch.'). It stops short of naming when-not-to-use cases such as survey blocks (set_survey), which keeps it from a 5.

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