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

readOnlyHint=true already covers the safety profile, so the description earns credit by disclosing the return payload (addresses, life-to-date/YTD/last-gift summary, individuals and their contact methods, custom fields). It stops short of noting pagination, latency, or permission requirements, but the return-content disclosure is substantive given no output schema.

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, front-loaded with the action and followed by the payload breakdown, with no filler. The field enumeration is dense but each item conveys what the caller receives, so little is wasted.

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 and a single required parameter, the description is the main carrier of return-value information and it does cover the response shape adequately. The main omission is any guidance on behavior when the contact_id does not exist or is inaccessible.

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 100% for the single contact_id parameter, so the schema already carries the parameter documentation. The description adds only mild context by naming entity types a contact can represent and citing the API path form, which is the expected baseline when the schema does the heavy lifting.

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?

States a specific verb and resource ('Fetch one contact') and enumerates the categories (household, organization, foundation) and payload contents, so the agent knows this is a single-record read. It does not explicitly contrast itself with virtuous_find_contact or virtuous_search_contacts, so sibling differentiation is left implicit.

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 implied by 'Fetch one contact' plus the underlying GET /api/Contact/{contactId} pattern, telling the agent this is the by-id lookup. No explicit when-to-use, when-not-to-use, or alternative tool routing is provided, so the agent must infer that search_contacts/find_contact are for discovery rather than direct retrieval.

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