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

Annotations already establish readOnly, idempotent, non-destructive behavior. The description adds meaningful behavioral context beyond that: the log is ordered newest first, each entry carries section id/title, HMRC's change note, published_at, and age_days. It does not discuss pagination or rate limits, but it sufficiently characterizes the returned data for a read-only listing tool.

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 compact and front-loaded: the first sentence states the core action and output ordering, and the second sentence efficiently adds returned fields and concrete use cases. No sentence is wasted and the examples of HMRC change notes make the tool's purpose tangible without bloating the text.

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?

There is no output schema, so the description carries the burden of explaining return values; it does so by naming the fields and sort order. It does not explicitly tell the agent how to choose between this and the closely related hmrc_manual_search/hmrc_manual_section siblings, but the core calling context and data expectations are sufficiently covered.

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%, with all four parameters (manual, limit, since, section_id) already clearly documented in the input schema. The description adds framing that the tool returns a revision log, but does not meaningfully enhance parameter-level semantics beyond the schema, so baseline 3 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?

The description uses a specific verb-resource pair ('Read what HMRC most recently changed in one of its internal manuals') and clarifies it is a per-section revision log published newest first. This clearly distinguishes it from sibling tools like hmrc_manual_search, hmrc_manual_section, and hmrc_manuals, which target current guidance or full manuals rather than change history.

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 explicitly lists when to use the tool: to tell whether HMRC's position has moved, audit manual freshness, or watch a specific area for revisions. It does not name alternative tools or provide explicit exclusions, so it stops short of fully routing the agent, but the intended use cases are clear.

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