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

The readOnlyHint annotation already establishes this as a safe read, but the description adds real value beyond it by disclosing the shape of the returned record (giving summary, individuals, contact methods, custom fields). With no output schema present, this return-content disclosure is what lets an agent plan follow-up calls. It still omits error behavior for an invalid/nonexistent ID and any authorization or rate-limit constraints.

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 dense but well-front-loaded sentence covers purpose plus payload, followed by a short API endpoint reference. Nothing is padded or redundant, and the core action is stated first.

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 one-parameter, no-output-schema read tool, the description covers what comes back and effectively implies the ID-based lookup workflow, which is enough for correct invocation. Missing only failure-mode and permission context, which are secondary here.

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% and the single parameter (contact_id, integer > 0) is fully documented in the schema, so the baseline is 3. The description adds no extra semantics such as ID sourcing or format beyond the schema's own constraint.

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 (fetch) and resource (one contact), and enumerates the payload contents: address, giving summary (life-to-date, YTD, last gift), individuals and contact methods, and custom fields. The singular 'one contact' implicitly separates it from the search/list siblings, but it never names an alternative such as virtuous_find_contact or virtuous_search_contacts to make that distinction explicit.

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: the required contact_id and the single-record wording suggest 'call this when you already have one contact's ID.' There is no stated when-not-to-use, no guidance on how to obtain the ID (e.g. via virtuous_search_contacts), and no mention of behavior when the ID does not exist.

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