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

Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds meaningful behavioral detail beyond that by enumerating the returned fields, including withdrawal status and freshness indicators (published_at, source_last_modified, age_days), which helps an agent understand output contents and how to judge currency. It does not contradict the annotations.

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 two sentences with no filler. The first sentence front-loads the action and input modes; the second concisely lists the return contents and their purpose. Every clause 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?

For a read-only single-section retrieval tool, the description covers both input modes and the full set of output fields, and it explains why the freshness fields matter. Combined with complete schema descriptions and safety annotations, an agent has everything needed to call the tool correctly.

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 coverage is 100%, so the description is not required to compensate. It adds value by explicitly stating that base_path is an alternative to the manual-plus-section_id combination, which clarifies a relationship not fully spelled out in the schema. The example 'EIM42750' also grounds the section_id format.

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 ('Retrieve') and resource ('full text of one section of an HMRC internal manual'), and it differentiates from siblings by emphasizing a single section lookup. It also clearly identifies the two accepted input modes, which distinguishes it from hmrc_manual_search and hmrc_manual_changes.

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 makes the intended usage clear: when you have a section identifier or base path and need the full text. It does not explicitly name alternatives or state exclusions, but the contrast with sibling tools (search, changes) provides enough context for an agent to select this tool.

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