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

Annotations already declare readOnlyHint and destructiveHint=false, so 'Read-only' is partly redundant but confirms the profile. The description adds genuinely new context: returned values may contain personal data and SECRET-typed variables are always redacted, which is a behavioral trait the schema cannot express.

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?

Four short sentences, each earning its place, with the return scope front-loaded and the prerequisite placed last where it is acted on. No filler or restatement of the tool name.

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, the description still states what is returned (full profile plus all contact-variable values), the redaction behavior on returns, and the prerequisite lookup. Nothing needed to call this two-parameter read tool correctly is missing.

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 coverage is 100% and the schema already documents both contactId (including 'as returned by list_contacts or send_message') and the applicationId default/fallback behavior. The description's 'call list_contacts first' adds workflow framing but restates schema content, so baseline 3 applies.

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?

A specific verb ('Return') plus a precise scope: one contact's full profile and every stored contact-variable value. This clearly separates it from list_contacts and get_contact_activity, which an agent can distinguish without opening either schema.

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?

'Call list_contacts first to find the contactId' gives an explicit prerequisite workflow. It stops short of stating exclusions or alternatives (e.g., when get_contact_activity is the better choice), so it is clear context rather than full when/when-not guidance.

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