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

The annotations only declare readOnlyHint=true, and the description adds genuinely useful behavior: the underlying Platform API endpoint (GET /open_channels) and the return envelope { channels[], next }, which tells the agent pagination is cursor-based. It does not state auth requirements, but for a read-only list endpoint the added context is solid.

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?

Three short sentences with no filler: purpose first, then endpoint, then return shape. Every sentence carries information and the most important clause is front-loaded.

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 no output schema, the description compensates by stating the return shape ({ channels[], next }) and the endpoint, and the fully documented schema covers all parameters. It is nearly complete for a simple read-only list tool, though it could note the read-only nature explicitly.

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 all five parameters (limit, token, custom_types, url_contains, name_contains) are already documented in the schema. The description adds no extra filter syntax or default behavior beyond the schema, 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?

States a specific verb and resource ('List open (public, participant-based) channels') and clarifies what 'open' means, which lets an agent distinguish it from sendbird_list_group_channels. It does not explicitly name the sibling alternative, so it stops short of a 5.

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?

There is no when-to-use or when-not-to-use guidance and no routing to alternatives such as sendbird_list_group_channels or sendbird_get_open_channel for a single channel. Usage is only implied by the resource name.

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