Create partner

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

Annotations only say this is not read-only and not destructive; the description adds the critical disclosure that is a 'Side effect: grants the user read access to the whole library'. That is exactly the kind of security-relevant consequence annotations cannot express, and it also notes the return shape.

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?

Front-loaded with the core action and the privilege consequence, and the Args/Returns block is short and scannable. The guidance sentence about list_users sits slightly awkwardly between the behavior statements, but nothing is genuinely wasteful.

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 single-parameter mutation with an output schema and basic annotations, the description covers action, prerequisite discovery, and the access-granting side effect. Missing only edge cases such as already-shared users or required permissions.

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 0%, so the description carries the burden and does so: it explains that user_id identifies 'the user to share with' and that the value comes from list_users. It still does not state the identifier format (numeric vs UUID) or whether self-sharing is valid.

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 gives a concrete verb and effect: 'Share this account's library with another user on the server', plus the consequence that the other user sees the photos alongside their own. This is far more informative than restating the name. It does not explicitly distinguish itself from update_partner/remove_partner, which is why it falls 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?

It gives actionable pre-invocation guidance — 'Find the id with list_users' — which tells an agent how to obtain the required identifier before calling. It does not mention when to prefer update_partner or remove_partner, or any preconditions such as an existing partnership.

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