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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds 'No sign-in', an authentication/access fact the annotations do not express, which is genuinely additive. It omits nothing critical for a single-record read.

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?

A single dense sentence that front-loads the identifier form, followed by a short access note. No wasted preamble. It runs slightly long by enumerating returned fields that the output schema already covers, but nothing is filler.

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?

An output schema exists, so return values need not be spelled out (the description does so anyway). Annotations carry the safety profile. The remaining gap is the unexplained `full` parameter and the absence of sibling routing, leaving the definition adequate but not complete.

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 only 50%: `ref` is described in the schema and the description merely repeats it ('ins_... or slug'), while the boolean `full` parameter is documented nowhere. With incomplete coverage and no compensating explanation in the description, it falls below the baseline 3.

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+resource: retrieve one instrument by ins_ id or slug, and enumerates what the record contains (YES semantics, tie rule, game, Kalshi ticker side mapping). That is more concrete than a bare 'look up a market', though it never explicitly contrasts itself with get_market or list_markets. An agent can infer scope but not the boundary against neighbours.

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?

There is no when-to-use or when-not-to-use guidance and no named alternative (e.g. get_market vs get_instrument). The only contextual signal is 'No sign-in', which is an access note rather than a routing rule. 'One instrument' implies single-item lookup, but that is purpose, not usage guidance.

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