list_known_crs

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

With no annotations, the description carries the full burden, and it does disclose two useful traits: the result is session-scoped and includes both pre-registered defaults and user-added definitions. However, it says nothing about how results are ordered or what each entry contains, and a listing tool's read-only safety profile is only inferred.

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?

One sentence with zero filler, front-loaded with the verb and resource, then the scope qualifier. Every clause earns its place.

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 parameterless listing tool with no annotations and no output schema, the description covers what an agent needs to decide to call it. The only gap is the shape of the returned entries, which is minor here.

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?

The schema has zero parameters, so there is no parameter semantics to document and the baseline of 4 applies. The description correctly implies a no-argument call, adding nothing that is contradicted or missing.

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 ('List CRS codes') and pins the exact scope ('currently registered with proj4 in this session'). It also names the counterpart operation, register_crs_definition, so an agent can distinguish listing from registration without opening a schema.

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?

Usage is implied rather than stated: the description makes clear this is the read side of the CRS registry, but it never says when to call it versus siblings like get_project_crs or register_crs_definition. No exclusions or preconditions are given.

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