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

With no annotations, the description carries the full burden and delivers: it discloses cost ('no energy, no action slot'), auth behavior ('no auth needed,' and that an api_key logs the watch on the match record), and a scoring caveat ('Nothing about the fly scores'). Only a fuller statement of side effects or rate behavior is missing.

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?

Content is dense but front-loaded: the return values lead, then cost/auth/scoring caveats follow. Every sentence carries information, though the parenthetical '(world_info says)' and the list of tallies make it slightly busy.

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?

No output schema exists, yet the description enumerates the returned fields, and it covers cost, auth, and scoring side effects. For a two-optional-parameter read tool this is nearly complete, with only explicit alternative-tool routing left unaddressed.

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 both parameters are already documented in the schema, including api_key and lobby_id semantics. The description's mention of auth and 'your own match when authenticated' echoes the schema without adding syntax or format detail, so the baseline 3 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?

States a specific verb and resource ('watch the fly') and then enumerates the returned facts (region, tenure, whom it follows, last feeder, season tallies). This clearly distinguishes it from siblings like swat_fly, feed_fly, and world_info, which the agent could otherwise confuse it with.

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 scopes use with 'on a match that hosts one (world_info says),' telling the agent the precondition for a meaningful call, and notes it is free. However, it never explicitly contrasts when to use watch_fly versus inspecting the fly via other tools or why one would bother beyond curiosity.

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