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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered; the description goes further by stating "Takes no input" and that no assignments or boosts are computed, which tells the agent this is a pure catalog lookup with no derived work. An output schema exists, so the absence of return-value detail is not a 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?

Three sentences, front-loaded with the resource and its output, then the no-input note, then the namespace warning. Tight overall; "business metadata" is slightly vague jargon but not padding.

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 zero-parameter read-only catalog endpoint with an output schema and readOnly/openWorld annotations, the description covers what the tool returns, what it does not do, and the namespace hazard that would most likely cause a wrong-ID error. Nothing critical is missing.

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?

The tool takes zero parameters (schema is an empty object with additionalProperties:false), so there is nothing for the description to disambiguate. The baseline for a no-parameter tool 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?

The description names a specific verb and resource ("Get the native FC27 manager-league modifier catalog") and bounds the scope by saying it returns source IDs and business metadata "without computing assignments or boosts." That negative scope distinguishes it from the manager/manager-facets siblings that would otherwise look similar by name.

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 clear consumption instruction — "Use these source modifier IDs when reading manager-league metadata" — and explicitly excludes two confusion cases: generic player league IDs and manager facet queryValue selectors. It stops short of naming a specific sibling tool to call before or after this one, so it is strong context rather than full when/when-not routing.

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