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

The description clearly describes a state-mutating tool: 'Maintain', 'Set merge=true to update existing items', 'set merge=false to replace the entire list', and marking items completed. This directly conflicts with the provided readOnlyHint=true annotation, which asserts no writes. The contradiction undermines the annotation.

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-loads purpose, then usage, then parameter semantics, then a UI note. Mostly efficient, though the merge=true/false sentence duplicates the schema description and the status list repeats the enum verbatim.

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?

Covers purpose, triggers, merge behavior, status workflow, and even renders the effect in the UI sidebar, which is enough to invoke the tool correctly. Minor gaps: no mention of what is returned or how id collisions behave, though no output schema exists to carry that.

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. The description goes beyond the schema by specifying the lifecycle semantics for status values ('mark in_progress before starting, completed immediately after finishing', 'only one item in_progress at a time'), which the raw enum does not convey; the merge explanation largely restates 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 a specific verb-and-resource pair ('Maintain a structured todo list for the current task') and immediately scopes it to task tracking. No sibling tool competes for this domain, so the agent can unambiguously identify it.

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 explicit trigger conditions ('three or more distinct steps', 'planning a complex multi-step task', 'tracking progress') and in-lifecycle rules for when to mark items in_progress vs completed. It stops short of naming when NOT to use the tool or any alternative for lighter requests.

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