twitter_x_user_stream_add_user

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

Annotations already indicate it's not read-only (readOnlyHint=false) and not destructive (destructiveHint=false). The description adds context by saying 'watch an X account' implying a monitoring setup, but it doesn't explicitly disclose potential side effects like creating a monitor or adding to an existing stream. However, it doesn't contradict annotations, and the annotation provides a baseline, so a score of 4 is appropriate.

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 bit verbose with the colon-separated explanatory phrase and the migration note, but it remains focused and informative. It could be slightly more concise, but every sentence adds value (purpose, migration context, cost).

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?

Given there is no output schema, the description doesn't explain what the tool returns, but it's a compat drop so the output might be implied. It covers the main purpose, usage, and the existence of an alternative. It doesn't mention error conditions or limitations, but for a simple one-parameter tool, it is reasonably complete.

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 only parameter (x_user_name) is described clearly: 'The X username to watch, without the @.' This provides both the meaning and format. Schema coverage is 100%, and the description adds value by specifying the absence of '@'.

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 clearly states the tool's purpose: 'watch an X account for new posts' and explicitly distinguishes it from twitter_monitor_create by positioning it as a compat drop for migration. The verb 'watch' and resource 'X account' are specific, and it differentiates from the sibling tool twitter_monitor_create.

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 explicit usage guidance: 'Prefer twitter_monitor_create for new integrations; this exists for migrating an existing x_user_stream-shaped integration without a rewrite.' It also notes 'Free per call' which is a cost consideration. This clearly indicates when to use and when to avoid the tool.

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