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

Annotations cover the safety profile (readOnly=false, destructive=false, idempotent=false, openWorld=false), and the description adds real behavior beyond them: settings are merged over type defaults, out-of-range indexes are clamped/appended, and a bare insert yields a sensible default block. It stops short of failure modes or validation behavior.

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 sentences, front-loaded with the action and position, then optional-field behavior, then the prerequisite tool. Slight redundancy between 'Provide the block type and the 0-based at_index' and the schema, but nothing is wasted.

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 non-idempotent mutation with no output schema and nested settings, the description supplies the merge semantics, index clamping, default behavior, and a prerequisite read tool, which is enough to call it correctly. It does not describe what is returned after insertion.

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 baseline is 3, but the description still adds meaning: the 0-based indexing convention with 0=top, append-on-overflow behavior, and the merge-over-defaults semantics of settings that the schema's terse 'merged over the block type's defaults' only gestures at.

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 precise verb+resource (insert a new block into a template) plus the positional scope, which is enough to separate it from meisa_update_template_block and meisa_move_template_block without opening any schema. The word 'new' makes the create-vs-edit distinction explicit.

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 concrete prerequisite workflow: 'Use meisa_get_template_blocks first to decide the index.' It never names the competing alternative (updating an existing block) or states exclusions, so it is strong context rather than full when/when-not routing.

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