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

Annotations already declare readOnly/idempotent/non-destructive, but the description goes well beyond them: it discloses where changes are saved (/setup), the reconnect flow per client (Claude/ChatGPT ask for reconnection with a new token; other apps disconnect/reconnect), and hard behavioral prohibitions (relay returned steps, never tell the user to remove the connector, never ask for ids or credentials).

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-loads the core purpose in the first clause, then layers routing conditions and behavioral rules. It is long, but nearly every sentence carries decision-relevant information; the reconnect detail and the 'never tell the user to remove the connector' rules are dense but earned.

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-required-param read tool with no output schema, the description covers purpose, routing, the change/reconnect workflow, and the agent's obligations. There is no meaningful gap an agent would need filled before calling it.

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?

There is a single optional parameter (response_format) at 100% schema description coverage, so the schema fully documents it. The description adds nothing about the parameter or its format tradeoffs, which is the expected baseline when the schema does the work.

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?

States a specific verb and resource: it returns the connected profile's leagues, teams, full custom rules, plus the steps to add/remove/change a league. It also distinguishes itself from the plain-listing siblings by telling the agent not to call it merely to start a session and noting it replaces fantasy_manage_setup.

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?

Explicitly gives when-not (the server instructions already list the connected leagues, so don't call it just to start a session) and when-to (leagues absent from context, rules truncated, list ends '…and N more', or the user wants to change their setup), with concrete trigger phrases. This is about as routed as a description gets.

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