set_block_description

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

Annotations indicate a write operation (readOnlyHint=false) and non-destructive (destructiveHint=false). The description adds meaningful behavioral context: persistence ('Saved in the file'), the refusal condition, and the clearing behavior. It does not contradict annotations and covers the key side effects.

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?

The description is efficiently organized: the core action first, then purpose, then content guidance, then constraints. Every sentence contributes value without redundancy. It is appropriately detailed for the task.

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 no output schema, the description covers all necessary aspects: what to write, how to clear, and when it may fail. It leaves no critical ambiguity for an agent to invoke it correctly.

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 50% (name is documented, description is not). The description compensates thoroughly by explaining exactly what the description parameter should contain ('Say what one row represents... Do not restate the field names') and how to clear it. This adds substantial meaning beyond 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 specific verb and resource: 'Write what a block is for, in prose, onto the block itself.' It clearly distinguishes this from sibling tools by contrasting with describe_block (which reads) and by emphasizing the prose, non-field-name content. The action is unambiguous.

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 provides clear context for when to use the tool (to document a block for future agents) and includes a specific refusal condition ('Refused when the block reserves `modifyDescription` to its owner'). It also explains how to clear a description via empty string. It does not explicitly name alternatives beyond implying describe_block, but the guidance is sufficient.

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