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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is clear. The description adds valuable context by specifying the return format (Markdown) and listing what content is included (fields, links, recent records, sources, licence), which is helpful given the absence of an output schema. It does not cover error handling or rate limits, but for a simple read operation this is adequate.

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 with zero waste. The first sentence front-loads the core purpose and output details, and the second efficiently distinguishes the tool from its sibling. No extraneous words.

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?

Given a single required parameter and no output schema, the description adequately explains what the tool returns (Markdown with specific content) and how it relates to a sibling. It could mention error behavior if the id is not found, but for a straightforward read tool it is sufficiently 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 100% and the single parameter 'id' is described as 'Entry id' in the schema. The description adds meaning by stating the id comes from search, which helps an agent understand where to obtain the value, going beyond the schema's minimal description.

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 (fetch) and resource (Thea entry) and explicitly differentiates from sibling thea_entry by contrasting output formats (Markdown vs JSON). An agent can immediately understand what this tool returns and how it differs from the nearest alternative.

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?

Implies the id comes from search results and explicitly names thea_entry as the JSON alternative, giving a clear condition for choosing this tool over that sibling. However, it does not address other siblings like thea_find or thea_search, leaving some ambiguity about when to use this versus those tools.

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