add_item

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

Beyond the annotations, the description discloses important behavior: it creates a new item or replaces an existing one with the same primary key, and it shows how to prevent overwrites using condition_expression. It also mentions the return value. This adds meaningful context not available from annotations alone.

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?

The description is well-structured with short, focused sections. Every sentence adds value: precise operation, overwrite nuance, usage guidance, and return type. No filler or redundant content.

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?

Given the tool's complexity, the description covers the essential aspects: what it does, when to use it, when not to use it, key parameter semantics, and the return value. An output schema exists, so detailed return field documentation is unnecessary.

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?

Even though context signals report 0% schema description coverage, the tool description fully compensates by explaining table_name, item (including the requirement to include partition/sort keys), and condition_expression with a concrete example. This gives an agent enough semantic detail to construct valid arguments.

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 opens with a specific verb+resource: "Add (put) a single item to a DynamoDB table," clearly identifying the action and target. It further distinguishes itself from siblings by explicitly listing when NOT to use it, naming update_item and bulk_add_items as alternatives.

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?

The description provides a dedicated "When to use" and "When NOT to use" section, with concrete alternatives (update_item for partial updates, bulk_add_items for batch operations). This gives an agent clear decision criteria for tool selection.

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