threads_lookup_profile

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

With no annotations, the description carries the full behavioral burden and does well: it discloses the required permission scope, the follower-count gate, and the restricted account allowlist under standard access. It does not say what is returned or how errors/private accounts surface, so it stops short of 5.

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?

A single sentence with the core action front-loaded, followed by the access constraints. Every clause carries actionable information; nothing is filler.

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 read tool with no annotations and no output schema, the description covers eligibility thoroughly. The remaining gap is that it never indicates what the returned profile contains, which matters somewhat when no output schema exists.

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?

Only one parameter, and the schema documents it at 100% coverage ('exact match, without @'). The description reinforces the lookup key ('by username') but adds no format or edge-case detail beyond the schema, so baseline-plus 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?

States a specific verb and resource: looking up a public Threads user's profile by username, with the parenthetical 'Profile Discovery' signaling the third-party discovery mode. This implicitly separates it from threads_get_profile (own profile) and threads_get_profile_posts, though it never names those siblings explicitly.

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?

Gives concrete eligibility conditions: requires threads_profile_discovery permission, the target must have >=100 followers, and under standard access only @meta, @threads, @instagram, and @facebook are queryable. That tells the agent when the call will fail, but no explicit 'use X instead' routing to a sibling tool.

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