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

Annotations already declare readOnlyHint, non-destructive, and closed-world, so the safety profile is covered. The description adds genuinely new behavioral context beyond them: the brief is immutable after the Sunday it was written, which matters for citation and caching decisions. It does not describe the response shape or what a 'brief' contains, which is a modest gap.

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: the resource plus key first, then the immutability rationale, then the routing pointer. Every clause carries information and nothing is repeated from the schema or annotations.

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 two-parameter read tool with annotations covering safety, the description covers what to pass, why the result is citable, and where to find valid weeks. The main omission is that with no output schema, the agent is never told what a 'brief' actually contains or its approximate shape.

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?

With 50% schema description coverage, the description does useful compensating work by supplying the concrete ISO week format and an example ('2026-W38') that the pattern-only schema leaves abstract. The second parameter (locale) is documented in the schema itself but unmentioned in the description, so the added meaning is real but partial.

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 names a specific resource ('One week's brief') and its retrieval key ('by ISO week, e.g. 2026-W38'), so an agent knows exactly what it gets back. It does not explicitly contrast with the sibling latest_brief, which is the closest ambiguous alternative, but the 'permanent address / by ISO week' framing implicitly separates an addressed lookup from a latest-item fetch.

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?

It gives a concrete routing rule: 'Call list_briefs for the weeks published,' which tells the agent when this tool is the wrong choice. It also implies the citation use case via 'safe to cite.' It stops short of stating when-not conditions (e.g., if the week is unknown or unpublished), but the alternative is named explicitly.

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