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

It goes beyond the annotations by explaining the immediate side effect: 'Anything shared with the team — toolboxes, connections — becomes available to them immediately.' It also describes the exact return shape (TEAM record like team.get, with member_count refreshed) and explicitly notes it does not return a membership record. This is substantial behavioral disclosure for a mutation with only false hints in 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?

The description is three dense sentences with no filler. Each clause earns its place: the core action, the non-invite caveat, the immediate accessibility consequence, and the return format. It is front-loaded with the verb and object.

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 only two required parameters, a complete input schema, and no output schema, the description covers the key operational facts: preconditions, side effects, and return semantics. The only information an agent might want but is absent is duplicate-add behavior, which is minor. Overall the definition is self-sufficient.

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?

The input schema already fully documents both team_id and user_id, including the user_id format constraint, so the baseline is 3. The description reinforces that user_id refers to an existing member and references member.list for ID lookup, but doesn't add material format or meaning beyond the schema. It is adequate but not a major compensation for a coverage gap because there is no gap.

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' with a precise object: 'an existing organization member to a team.' It immediately distinguishes itself from invitation workflows by stating 'This does not invite anyone,' and clarifies this is a membership operation rather than a creation or invitation tool. This clearly separates it from siblings like invite__create and team__create.

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?

It provides an explicit precondition: the person 'must already be a member (member.list),' and tells the agent where to get the relevant IDs. It also states the operation's scope boundary — 'does not invite anyone' — so an agent won't use it for invitations. It lacks a named alternative tool, but the context is clear.

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