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

Annotations already declare readOnly, idempotent, non-destructive, and open-world behavior, so the safety profile is covered. The description adds genuinely useful behavior beyond that: it discloses that this returns summary-level fields only and that full text lives in a separate resource, which prevents an agent from expecting complete entry content.

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?

Two sentences, zero filler. The field list is front-loaded so an agent can decide relevance immediately, and the usage/alternative note follows in a compact clause rather than a separate paragraph.

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?

There is no output schema, and the description compensates by naming the returned fields explicitly. Combined with the pointer to the full-text resource and the post-search placement guidance, an agent has everything needed to call this correctly and interpret the result.

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?

With a single parameter at 100% schema description coverage, the schema already documents the id and even gives a format example. The description's "by id" adds no format, resolution, or error semantics beyond that, 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 ("Get one codex entry by id") and then enumerates exactly what comes back: name, aliases, kind, world, summary, games, and the codex.slopped.site page. That level of specificity clearly separates it from the sibling search_codex, which returns multiple entries.

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?

Gives explicit sequencing ("Use after search_codex") and names the alternative for the full text (the slopped://codex/{id} resource). An agent knows both when to reach for this tool and where to go when the summary fields are insufficient.

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