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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds real value beyond that: the auth gate, the meaning of null for mergeable, the mergeState status vocabulary, and that the probe is the same one the merge gate uses. However, it discloses no failure modes (missing PR, permissions beyond auth) or response envelope behavior.

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 content is front-loaded and every clause maps to a real return field, so little is wasted. But it is delivered as one semicolon-chained run-on spanning three payload groups (record, mergeState, conflictRisk), which is hard to parse; a short structured breakdown would convey the same facts more clearly.

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?

With no output schema, the description legitimately must describe return shape, and it does so thoroughly for the mergeability and conflict-risk fields, including enum vocabularies. The auth preconditions are stated. Minor gaps remain around error behavior and how this differs from the status-summary sibling, but an agent can call it correctly from this text.

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% across all three required parameters (owner, repo, number), so the schema carries parameter meaning fully. The description adds nothing about parameter formats or constraints, which is acceptable at full coverage but earns only the baseline.

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 opens with a specific verb and resource ('Fetch the full detail record of a pull request') and enumerates what the record contains (title, body, state, branches, draft, author, timestamps) plus the conflict-probe enrichments. It implicitly distinguishes itself from list/status siblings by emphasizing full detail plus mergeable/mergeState/conflictRisk, though it never names an alternative tool 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?

The only explicit usage condition is the authentication requirement ('Authenticated callers only, the read tool surface still works anonymously'), which is genuinely useful preconditioning. There is no guidance on when to prefer this over merjax_pr_status_summary, merjax_list_pr_conflicts, or merjax_get_diff, so the agent must infer the selection.

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