Add a raw block to a channel

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It explicitly states that the tool operates 'WITHOUT image validation', which is a key behavioral trait and potential limitation. However, it does not mention other aspects like whether the operation is reversible, idempotent, or what the response looks like. Still, the critical caveat is disclosed, so it earns a 4.

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 sentence that is concise, front-loaded, and contains no unnecessary words. Every phrase adds value: the action, the input types, the validation caveat, and the sibling tool reference. Excellent structure.

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 there are no annotations, no output schema, and 0% schema coverage, the description needs to be self-sufficient. It explains the core behavior and distinguishes from a sibling, but it omits details about the optional parameter, expected return value, and any error cases. For a simple tool, this is close to adequate but still has notable gaps, warranting a 3.

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 0%, so the description must compensate. It clarifies that the 'value' parameter accepts a URL or Markdown text, which is essential. However, it does not explain the optional 'description' parameter or explicitly define 'channel_slug', though 'channel_slug' is fairly inferable from the name. The description adds some semantics but leaves gaps.

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: 'Add a block from a URL or Markdown text'. It distinguishes from sibling tool arena_add_product by explicitly saying 'For products prefer arena_add_product'. The 'WITHOUT image validation' also clarifies a specific scope, making the purpose distinct and unambiguous.

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 explicit guidance on when to use this tool: for raw blocks from URL or Markdown, and when not to use it by naming the alternative (arena_add_product) for products. This is a clear when/when-not statement with a specific alternative, exceeding the minimum.

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