update_registry_item

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

The description adds the key behavioral detail beyond annotations: it explicitly states that all fields must be supplied because it is a full replace. This is crucial because it signals that omitted fields will be overwritten, which is not evident from annotations alone. The annotations already flag destructiveHint: true, so the description complements rather than contradicts, providing specific operational semantics.

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 a single, focused sentence that front-loads the primary action and then states the critical caveat. There is no wasted text, and the full-replace behavior is presented immediately after the action, making it easy to parse.

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?

With 7 required parameters, low schema coverage, and no output schema, the description only covers the full-replace behavior. It does not provide individual parameter semantics or any information about what the tool returns (since there is no output schema). An agent would lack the detail needed to correctly supply all fields, particularly the ones without schema descriptions. The description is too sparse for a complex mutation tool with all-required parameters.

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 only 29% (only collection_id and collection_item_id have descriptions). The description does not explain the other five parameters (quantity, group_gift, marked_fulfilled, personal_note, most_wanted) at all. It only mentions that all must be supplied, which is a general requirement but does not clarify their meaning or expected formats. Given the low schema coverage, the description fails to compensate, leaving significant ambiguity for the agent.

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 clearly states the action ('Update an existing registry item') and the critical behavior ('it's a full replace'). This distinguishes it from sibling tools like add_registry_item and remove_registry_item by indicating it modifies an existing item rather than creating or deleting.

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 implies usage for updating an existing item but does not explicitly state when to choose this tool over alternatives (e.g., 'use this when you need to modify an existing item; for new items use add_registry_item'). The 'full replace' note hints at a requirement, but there is no explicit when-not or alternative routing, leaving the agent to infer from sibling names.

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