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

Annotations already declare readOnlyHint=false and destructiveHint=false. The description adds genuinely useful behavioral context: 'It reaches no one, so it runs without asking' (no notifications/side-effects) and the auth requirement ('Needs the user's Cotlet API key with access to this app'). It does not explain silent-failure or duplicate-item behavior, but it meaningfully supplements the annotations.

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 the action and resource, and every sentence carries information. There is mild redundancy in repeating 'to your Items list' and 'Saves an item', but it stays compact and readable.

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 simple create tool with full schema coverage and no output schema, the description covers purpose, reuse context, notification behavior, and auth. Nothing critical to correct invocation is missing, though alternative-usage guidance would round it out.

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 description coverage is 100%, so the schema already documents name, rate, and description. The description restates these fields without adding format or constraint detail beyond what the schema provides, so the baseline of 3 applies.

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 ('Save a service or material to your Items list') and clarifies what is created (an item with name, rate, optional description). It clearly distinguishes from siblings like joist_list_items and joist_create_estimate.

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 a reason to use it ('so it can be reused on later estimates'), implying the when-to-use context, but names no alternatives (e.g., joist_list_items) and states no exclusions or preconditions beyond the API key note.

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