add_to_block_list

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

With no annotations, the description carries the burden. 'Add... to an existing block list' clearly indicates a mutation, but it does not disclose side effects, idempotency, whether duplicates are allowed, or if changes are reversible. This is minimal but not misleading; it provides the core behavioral trait (adding URLs) but lacks deeper disclosure.

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?

A single, clear sentence with no filler or redundancy. It fully captures the action and scope without wasted words.

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 two-parameter mutation, the description is adequately complete: it names the action, the resource, and the precondition ('existing'). No output schema is present, so return details are not required. The sibling tools provide additional context for list management, but the description itself is sufficient for basic use.

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% with descriptions for both parameters. The description adds extra meaning by specifying 'publisher URLs' (not just any URLs) and 'existing' block list (not creation). This goes beyond the schema's generic 'Block list ID' and 'URLs to block', enriching the semantic context.

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 uses the specific verb 'Add' and clearly states the resource: 'publisher URLs to an existing block list.' This distinguishes it from sibling tools like create_block_list (new list), remove_from_block_list (removal), and list_block_lists (listing).

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 phrase 'existing block list' implies the tool is for modifying an already-created list, which gives some context. However, it does not explicitly mention alternatives or when not to use this tool (e.g., use create_block_list if the list doesn't exist). Sibling names provide hints but the description itself offers no direct guidance beyond the implied precondition.

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