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

Beyond the annotations, it discloses the real consequences of sharing: the recipient operates the same live run, can abort it, answer its approval prompts, and take the next turn, and no account or invitation is created. This is meaningful behavioral context. It does not address what happens when the same email is shared twice (relevant given idempotentHint=true), which keeps it below a 5.

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 sentences, the access grant and the reciprocal capabilities are front-loaded, and the account caveat lands last where it belongs. Every clause carries information; nothing is padding.

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 two-parameter, non-destructive tool with a complete schema and annotations, the description covers purpose, prerequisites, and the recipient's resulting powers — enough to call it correctly. The main residual gap is repeat-share behavior and the absence of any note on what the call returns.

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% and both parameters are already documented in the schema, including the account prerequisite for email and the source of session_id. The description reinforces that prerequisite but adds no new format or semantics, so the baseline 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?

"Give a teammate access to a campaign by email address" states a specific verb (give access) and resource (campaign) via a concrete mechanism (email). It is clear enough to distinguish from abort_campaign or check_campaign, though it never names its inverse sibling unshare_campaign.

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 says clearly when to use it — granting a teammate access, even mid-run — and states the prerequisite that the person must already have an account. It does not explicitly cover when not to use it or point to unshare_campaign/list_campaign_access as alternatives, so it falls short of a 5.

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