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

Annotations already declare readOnlyHint=false, destructiveHint=true and openWorldHint=false. The description adds real behavioral context beyond that: 'The board's rules for new cards run, as in the app,' which explains why a create call can have side effects, plus the Pro constraint that recurrence requires a due date. It does not explain return values, but for a create tool with annotation coverage this is solid.

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 core action and resource before feature details. The parenthetical Markdown enumeration is the longest stretch and borders on padding, but it is informative enough to earn its place.

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 an 8-param tool with nested objects and no output schema, the description covers creation semantics, target resolution, content format, side effects, and Pro constraints. The main omission is what the call returns (e.g., the created task identifier), which an agent may need for follow-up calls.

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 only 63%, and the description compensates meaningfully: it documents that the `description` field becomes the card page and accepts Markdown (a detail absent from the schema), that recurrence is Pro-gated and needs a due date, and enumerates the optional features (due date, reminders, checklist). It adds utility beyond the structured fields, though not every undocumented param is covered.

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?

The description states a specific verb and resource ('Adds a task (card) to a list') and further specifies the fallback ('or to a board's first list when only boardId is given'). It also implicitly distinguishes itself from siblings like create_task_from_template and bulk_tasks by describing scratch creation. An agent can identify exactly what this does without opening the 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?

It gives conditional usage for two parameters (use listId, or boardId alone to target the first list), which is genuinely helpful routing guidance. However, it never says when to prefer this over create_task_from_template, bulk_tasks, or add_checklist/add_reminder — usage relative to alternatives is left to inference.

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