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

Annotations already cover readOnlyHint and openWorldHint, so the bar is lower; the description still adds real semantics the annotations do not carry: results are grouped by list, a list is a tag, and only open todos appear by default. Return format beyond grouping and pagination behavior are left implicit, keeping it at 4.

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 short sentences: what you get, how it is shaped, the default filter, then the alternative action. The grouping/tag explanation is front-loaded and every sentence carries information the agent needs.

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 three-optional-parameter, read-only list tool with no output schema, the description gives enough structure (grouped by list/tag, open-only default) for an agent to predict the result. Pagination interaction between limit and grouping is not addressed, a minor gap.

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 the baseline is 3, but the description independently explains the 'list' parameter by clarifying that a list is a tag and giving the todo/groceries → "groceries" mapping, which is genuinely additive. It reinforces include_done's default behavior as well; limit is left to 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?

Names the specific resource (the user's todos) and describes the return shape ('grouped into their lists'), which is more than a restatement of the name. The tag equivalence ('a list is a tag (todo/groceries shows as "groceries")') pins down the data model. It stops short of explicitly contrasting with siblings like list_notes or list_tags, so it does not fully earn a 5.

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?

'Open todos only unless include_done is set' gives the default selection rule, and 'Use update_note with done: true to tick one off' routes the agent to the correct sibling for the adjacent write action. Lacks an explicit when-not (e.g., when to reach for list_notes instead), so not a 5.

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