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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful behavioral context beyond annotations by stating that authentication is required and by disclosing the specific fields returned, which matters since no output schema exists.

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 three short sentences with no filler: purpose, auth requirement, parameter source, and return fields. The repeated tool name 'getContact:' is a minor redundancy, but each sentence earns its place and the key information is front-loaded.

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 simple single-resource read operation with one required parameter and a well-documented optional sessionKey, the description covers what an agent needs: what the tool does, where the identifier comes from, authentication expectations, and return contents. No output schema exists, so the explicit return-field list is especially valuable.

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%, so the input schema fully documents both contactId and sessionKey. The description's mention of sourcing contactId from listContacts adds workflow context but does not materially extend the semantic detail already present in the schema.

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 a specific verb and resource: 'Get detailed information about a specific contact.' It also distinguishes itself from listContacts by targeting a single contact, and the included return fields (name, email, phone, organization, address) make the 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 gives practical usage guidance by telling the agent to obtain contactId from listContacts, which establishes the correct upstream workflow. It does not explicitly exclude alternatives such as getContactsForDomain, but the single-contact framing makes the intended use clear.

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