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

Annotations only cover the safety profile (readOnly=false, destructive=false). The description adds genuinely useful behavior: it is a merge/partial update, and operator slug, id, and createdAt are immutable. It omits auth requirements and error behavior, but the merge + immutability disclosure goes meaningfully beyond annotations.

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 sentences, front-loaded with the core action, then the merge semantics and immutability constraint. No filler; each clause carries distinct information.

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 an 8-param mutation tool with no output schema and 13% schema coverage, the description covers the mutation model and immutable fields but leaves half the parameters, return behavior, and auth context unaddressed. Adequate but with clear gaps.

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 only 13% (just the id param documented), so the description must compensate. It does partially by naming enabled, describe, and endpoint as updatable and flagging slug/id/createdAt as immutable, but leaves label, direction, credentialRef, and replyContract undocumented in both schema and description.

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+resource ('Update an existing channel') and enumerates concrete editable fields (enabled, describe contract, endpoint payload), so the agent knows exactly what the tool mutates. It does not explicitly name its siblings (attach_/delete_/list_operator_channels) for differentiation, so it lands just below the top.

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 channel' and the schema note that id comes from attach_operator_channel imply the precondition of a pre-existing channel, but the description never states when to use this vs attach/delete/test_operator_channels. Usage is inferable rather than explicit.

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