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

With annotations already covering the safety profile, the description adds substantial unannotated behavior: anonymous access is capped to the latest published month plus two calendar months, earlier months need OAuth with mcp:read, counts below twenty are suppressed, state categories overlap, 189 has no state distribution, and each request reads the currently published data. These are exactly the traits an agent cannot infer from readOnly/openWorld hints.

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?

Front-loaded with purpose before mode details, and no sentence is pure filler. It is dense and runs long for a single paragraph, but each clause (access tiers, suppression, pagination limits) carries functional information.

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 must characterize the return, and it does: English natural-language text with preserved sources, conditions and pagination, plus per-view result caps (six months, fifteen categories) and suppression rules. Nothing needed to invoke it correctly 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?

Schema coverage is high (89%), so the schema already carries most parameter meaning; the description reinforces which params pair with which view (history→fromMonth/toMonth, distributions→page) but adds little syntax or format detail beyond the schema. Baseline 3 is appropriate when the schema does the heavy lifting.

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 precise verb+resource ("Read SkillSelect EOI data") and enumerates the exact scope (subclasses 189/190/491 state nomination, four view modes), so the agent knows precisely what the tool returns. It stops short of naming any sibling tool (e.g. get_state_nomination or get_189_invitations), so differentiation is implied by topic rather than stated.

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 maps each view to its preconditions (points/states require occupation and month; history needs fromMonth/toMonth; distributions need page) and gives real operational routing ("Preserve the other filters when continuing, and stop when the user's question is answered"). But it never says when to pick this tool over the many sibling nomination/invitation tools, and no exclusions are given.

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