client_getProfilePicUrl

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only states the basic action without mentioning potential null returns, error conditions, network dependencies, or session requirements. For a read operation, this lacks depth and leaves behavioral assumptions unaddressed.

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, front-loaded sentence with no unnecessary words. It is concise and easily scannable, though slightly awkward grammatically. This is an exemplary level of brevity.

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?

The tool is simple (2 params, no output schema), and the description is mostly adequate. However, the presence of a closely related sibling tool 'contact_getProfilePicUrl' introduces ambiguity. The description does not clarify the distinction or provide enough context to ensure correct tool selection, making it incomplete in this context.

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 100% coverage with descriptions and examples for both 'contactId' and 'sessionId'. The description adds no additional parameter-related meaning beyond what the schema already documents, so the baseline score of 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 'Return the contact ID's profile picture URL' clearly states the action (return) and the resource (profile picture URL for a contact ID). It is specific and understandable, but it does not differentiate from the sibling tool 'contact_getProfilePicUrl', which likely serves a similar purpose.

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 provides no guidance on when to use this tool over alternatives. It does not explain the '[Client]' prefix or reference the similar sibling tool 'contact_getProfilePicUrl'. There are no explicit context cues or exclusion criteria.

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