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

With only readOnlyHint=false available, the description usefully discloses that the call mutates state (answering) and returns join credentials with both a token and a media url, which is valuable since there is no output schema. It omits failure behavior (expired invite, already-answered call) and any permission requirements for issuing credentials.

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?

Two compact sentences with no filler: the action and its input come first, the return value second. Every clause carries information the agent needs.

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 one-parameter tool with no output schema, the description covers the action, the id source, and the response shape, which is close to sufficient. What remains missing is edge-case behavior — what happens if the invite is stale or the call was already answered — which matters for a state-changing call tool.

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% for the single room_id, so the schema already carries the semantics; the description adds only the origin hint ('from the call_invite'). That hint also mildly conflicts with the schema, which attributes the invite to mDM_call_start rather than mDM_list, leaving the agent with two provenance stories.

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 ('Answer an incoming 1:1 call by its room_id') and names the return ('join credentials (token + media url) for the same room'). An agent can distinguish this from mDM_call_start and mDM_call_end without opening a schema.

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 'incoming 1:1 call' establishes the triggering context, and pointing to the call_invite as the id source tells the agent where to obtain the input. It does not explicitly name mDM_call_start/mDM_call_end as alternatives or state what to do when no invite is pending, so it stops short of full routing guidance.

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