gitlab_mr_reply

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

The readOnlyHint=false annotation already tells the agent this mutates state, so the bar is lower. The description usefully clarifies that the comment is nested inside an existing thread rather than creating a new one, but says nothing about permissions required, whether the discussion must still be open, or failure behavior when discussion_id is invalid.

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?

Two short sentences, zero filler, with the action front-loaded and the routing guidance immediately after. Every sentence earns 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?

An output schema exists, so return values need not be explained, and the four required parameters are fully documented in the schema. For a simple reply tool the description is nearly sufficient, though it omits any note on what happens when the discussion_id is stale or not found.

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 description coverage is 100%, including the non-obvious iid vs global id distinction and the origin of discussion_id (gitlab_mr_discussions or comment_on_line). The description adds no parameter meaning beyond the schema, 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 (reply) and a specific resource (an existing discussion thread), and the second sentence distinguishes the behavior from the alternative of opening a new thread on the same line. An agent can tell it apart from gitlab_mr_comment / gitlab_mr_comment_on_line conceptually without opening schemas.

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?

"Use it to answer a review comment instead of starting a second thread on the same line" gives a clear when-to-use condition and an implicit when-not (don't open a new thread). It does not name the sibling tool that creates a new thread, so the routing is behavioral rather than explicit.

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