Read a contact

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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds value by specifying the return contents (every email, phone, label, organisation, job title, postal addresses, links, notes), which is behaviorally relevant and not repeated in annotations. It does not contradict the annotations.

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?

The description is a single, tightly written sentence. It is front-loaded with the core purpose ('Read one contact in full') and then efficiently lists the return fields. There is no filler, and every phrase contributes useful information.

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?

Given the tool's simplicity (2 parameters, no output schema), the description covers what is needed: it explains the scope ('in full') and the specific fields returned. It does not list error conditions or explicitly state the absence of side effects, but annotations already cover safety, and the field list is adequate for an agent to understand the returned data. Overall, it is sufficiently complete for correct invocation.

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 input schema provides full descriptions for both parameters (account and resource_name), and the schema coverage is 100%. The description does not add additional parameter-level meaning beyond what the schema already states (e.g., it does not clarify the 'full' return structure or the role of each parameter). Per the baseline rule for high schema coverage, a 3 is appropriate.

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 states the action explicitly ('Read one contact in full') and enumerates the specific data fields returned (emails, phones, labels, organisation, job title, addresses, links, notes). This clearly distinguishes it from sibling tools like contacts_search (which searches) and contacts_list (which lists), making the tool's purpose unambiguous.

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 description implies usage: for a single known contact, use this tool. However, it does not explicitly state when to prefer it over contacts_search or contacts_list, nor does it mention any exclusions or prerequisites (e.g., that a resource_name is required). The guidance is implicit rather than explicit, so it falls short of a 4.

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