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

Annotations already declare idempotent=true and destructive=false; the description reinforces this by stating content, labels and citations are unchanged, which is valuable reassurance for a title mutation. It also discloses the return value ('Returns the source') despite there being no output schema. It does not mention permission requirements or failure modes.

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?

Two compact sentences plus an endpoint: the mutation and its scope come first, the alternative routing second, and nothing is wasted. No filler or redundant restatement of the tool name.

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, non-destructive mutation with no output schema, the description covers the effect, the non-effects, the size limit, the return value, and the alternative tool. Only edge cases like permission failures are absent, which is minor at this complexity.

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% and both parameters carry descriptions, so the schema already does the heavy lifting. The description's 200-character note simply restates the schema's maxLength rather than adding format or syntax guidance, so the baseline 3 is appropriate.

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 ('Set a source's title') plus the scope of the change (up to 200 characters). It also names the sibling it is not (notebook_append_to_source) for text changes, so an agent can distinguish it from the other rename/update tools without opening a 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 when-to-use condition and explicitly routes text edits to notebook_append_to_source, which is the most likely confusion point among siblings. It stops short of a full when-not list (e.g., title-only vs. label updates), but the essential alternative is covered.

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