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

Annotations already cover the read-only/non-destructive profile, and the description adds genuinely useful scope disclosure: resolving a link confers no membership or DM access. That is real value beyond structured fields. It stops short of noting failure behavior for malformed/expired tokens, so not 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, zero filler, with the core action front-loaded and the security caveat second. Nothing redundant with the title or schema.

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?

An output schema exists, so no return-value explanation is needed, and the read-only safety profile is covered by annotations. For a single-token resolver the description is nearly sufficient; only the invalid/expired-token outcome and any auth prerequisite are unstated.

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?

One required parameter with 0% description coverage; the description only echoes its meaning ('contact token') while the schema itself supplies the format constraint (pattern ^cl_[0-9a-f]{64}$). Baseline 3 is appropriate since the schema pattern is self-documenting and the description adds no semantics about expiry, single-use, or reuse.

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?

Specific verb+resource: 'Resolve a contact token' with a stated output ('the intended invitation recipient actor'). This is clearly distinguishable from sibling private_space_create_contact_link and from preview/accept invitation flows. It doesn't explicitly name an alternative, which keeps it at 4 rather than 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?

The 'grants no membership or private-message access' clause tells the agent what this is NOT, but there is no explicit when-to-use or routing statement (e.g., pair with preview_invitation vs accept_invitation). Usage is implied from the token-resolution framing rather than spelled out.

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