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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is covered. The description adds only the 'public' qualifier, which hints that private/suspended accounts may not resolve, but it says nothing about rate limits, failure behavior for missing users, or data freshness.

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?

Three short sentences with the capability front-loaded and the exclusion immediately after; nothing is buried. The trailing 'Required: username' is redundant with the schema's required array and is the only sentence that doesn't fully earn its place.

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 output schema, the description covers what it returns (profile fields plus follower counts) and which platform it targets, which is sufficient to call it correctly. Only the missing/private-account edge case remains undocumented.

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?

There is a single required parameter with 100% schema description coverage, including the at-sign pattern and length bounds. 'Required: username' merely restates the schema and adds no format or syntax detail beyond it, so the 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?

States a specific verb and resource ('Return a public X profile and follower counts') and names the scope ('by username'). It also rules out the most likely confusion by saying it is not posts or keyword search, so an agent can distinguish it from google_search and get_linkedin_profile (different platform) without opening the 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?

Provides an explicit exclusion ('Not posts or keyword search') with the correct alternative ('use google_search for indexed pages'). The positive 'when to use' case (wanting a profile or follower counts) is only implied rather than stated, which is the one gap.

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