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

The annotations already declare readOnlyHint=true and openWorldHint=false, so the safety bar is low. The description does add genuinely useful context beyond them — the response includes contact methods and an agent protocol that must be followed when contacting the person — but it says nothing about behavior when the id is unknown or about privacy constraints on the contact data.

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?

One sentence, front-loaded with the action and scope, with zero redundant wording. The notable payload — the contact protocol — is placed where it will be read.

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 no output schema, the description usefully previews what comes back (contact methods plus the protocol to follow) and covers the single required input. Only error/not-found behavior and id provenance are left unspecified, which is minor for a simple read 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?

There is a single parameter with full schema description coverage, so the schema does the heavy lifting. The description only reaffirms that lookup is 'by id' and adds no format, source, or validity detail beyond that.

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 names a specific verb and resource with explicit scope: 'Fetch one calling card by id'. That is clearly distinct from siblings like search_humans or list_topics, but it never names an alternative to contrast against, so differentiation is implicit rather than stated.

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?

There is no when-to-use or when-not-to-use guidance. The definition implies the caller already has a card id but never says how to obtain one (e.g., via search_humans) or when another tool is the better choice.

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