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

Annotations already establish readOnly, idempotent, non-destructive, closed-world behavior, so the description doesn't need to restate safety. It adds real value by disclosing the empty-state contract (card: null when none exists) and the shape of what is returned, which the annotations do not cover.

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 tight sentences: the retrieval scope is front-loaded and the null-return caveat follows immediately. No filler or restatement of the title.

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 zero-required-parameter read tool with a full output schema and rich annotations, the description is nearly self-sufficient; the return shape is covered by the output schema. Minor gap: it never connects itself to the create_or_update_card sibling that produces the card it reads.

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 single apiKey parameter is fully documented in the schema (baseline 3 at 100% coverage), including the note that it's only needed when no Authorization header was configured. The description adds nothing about parameters, which is acceptable given the schema does the work.

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?

Names a specific verb (Retrieve) and resource (the authenticated user's business card), and enumerates the resource's contents (contact details, social links, theme, lead-capture settings) plus its public URL. This makes it clearly distinct from write-oriented siblings such as create_or_update_card.

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?

Usage is only implied: an agent can infer this is the read path for the card, but the description never says when to prefer it over create_or_update_card or that it needs no inputs. No alternatives or conditions are stated.

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