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

Goes well beyond the annotations: the batch applies to the latest stored version including edits made on the site, the response shows the current diagram and what changed outside the chat, commands are applied in order with valid ones kept and rejected ones returned with reasons, and removing variables/links is called out as destructive (consistent with destructiveHint=true). It even discloses a capability boundary — "You never position anything."

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?

Front-loaded with purpose, then identifier format, then concurrency/response behavior, then the command catalog — nothing is wasted and every clause carries information. The command catalog is nevertheless a dense run-on paragraph that would scan better as discrete entries.

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 nested batch-mutation tool with no output schema, the description covers the input contract, identifier schemes, partial-failure semantics, concurrency against on-site edits, destructive operations, and the return content. An agent has enough to construct and interpret a call without further inference.

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?

With 0% schema coverage on a deeply nested oneOf, the description compensates substantially by enumerating every op name with its field sets (addVariable {tempId, name, description}, addLink {from, to, polarity, delay?, explanation}, updateLoop {loop…, name, description}, etc.) and by explaining the tempId convention (t1, t2) versus existing ids (v3, l4). It leaves some semantics unstated, notably what `delay` means, the temporal polarity wording, and the 200-command cap.

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 ("Change an existing diagram") and scopes it to existing diagrams, which distinguishes it from the siblings create_diagram and get_diagram without needing their schemas. The sentence about what a batch does reinforces that this is a mutation of an existing artifact.

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?

Explains that `diagram` accepts an id or a site link, that commands reuse existing variables, and that new loops must be named — practical guidance for constructing a call. It never states when not to use it (e.g. for a brand-new diagram, call create_diagram), so it stops short of a full routing statement.

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